All language subtitles for How the Earth was made 2009 HC 1080p BluRay EN sub_Subtitles01.UND

af Afrikaans
ak Akan
sq Albanian
am Amharic
ar Arabic
hy Armenian
az Azerbaijani
eu Basque
be Belarusian
bem Bemba
bn Bengali
bh Bihari
bs Bosnian
br Breton
bg Bulgarian
km Cambodian
ca Catalan
chr Cherokee
ny Chichewa
zh-CN Chinese (Simplified)
zh-TW Chinese (Traditional)
co Corsican
hr Croatian
cs Czech
da Danish
nl Dutch
en English
eo Esperanto
et Estonian
ee Ewe
fo Faroese
tl Filipino
fi Finnish
fr French
fy Frisian
gaa Ga
gl Galician
ka Georgian
de German
el Greek
gn Guarani
gu Gujarati
ht Haitian Creole
ha Hausa
haw Hawaiian
iw Hebrew
hi Hindi
hu Hungarian
is Icelandic
ig Igbo
id Indonesian
ia Interlingua
ga Irish
it Italian
ja Japanese
jw Javanese
kn Kannada
kk Kazakh
rw Kinyarwanda
rn Kirundi
kg Kongo
ko Korean
kri Krio (Sierra Leone)
ku Kurdish
ckb Kurdish (Soranî)
ky Kyrgyz
lo Laothian
la Latin
lv Latvian
ln Lingala
lt Lithuanian
loz Lozi
lg Luganda
ach Luo
mk Macedonian
mg Malagasy
ms Malay
ml Malayalam
mt Maltese
mi Maori
mr Marathi
mfe Mauritian Creole
mo Moldavian
mn Mongolian
sr-ME Montenegrin
ne Nepali
pcm Nigerian Pidgin
nso Northern Sotho
no Norwegian
nn Norwegian (Nynorsk)
oc Occitan
or Oriya
om Oromo
ps Pashto
fa Persian
pl Polish
pt-BR Portuguese (Brazil)
pt-PT Portuguese (Portugal)
pa Punjabi
qu Quechua
ro Romanian
rm Romansh
nyn Runyakitara
ru Russian
gd Scots Gaelic
sr Serbian
sh Serbo-Croatian
st Sesotho
tn Setswana
crs Seychellois Creole
sn Shona
sd Sindhi
si Sinhalese
sk Slovak
sl Slovenian
so Somali
es Spanish
es-419 Spanish (Latin American)
su Sundanese
sw Swahili
sv Swedish
tg Tajik
ta Tamil
tt Tatar
te Telugu
th Thai
ti Tigrinya
to Tonga
lua Tshiluba
tum Tumbuka
tr Turkish Download
tk Turkmen
tw Twi
ug Uighur
uk Ukrainian
ur Urdu
uz Uzbek
vi Vietnamese
cy Welsh
wo Wolof
xh Xhosa
yi Yiddish
yo Yoruba
zu Zulu
Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated: 1 00:00:05,964 --> 00:00:09,091 male narrator: Planet Earth is unique, 2 00:00:09,217 --> 00:00:14,513 an immense ball of rock 25,000 miles around. 3 00:00:14,639 --> 00:00:17,891 lt is a refuge, 4 00:00:18,018 --> 00:00:21,228 1/3 land, 2/3 water, 5 00:00:21,354 --> 00:00:23,480 and with an atmosphere rich in oxygen, 6 00:00:23,606 --> 00:00:26,233 it is the only known home in the universe 7 00:00:26,359 --> 00:00:27,901 for living creatures. 8 00:00:28,028 --> 00:00:30,154 But this blue-green oasis 9 00:00:30,280 --> 00:00:32,573 has not always been so welcoming. 10 00:00:32,699 --> 00:00:36,243 The planet bears the scars of a traumatic past, 11 00:00:36,369 --> 00:00:40,831 a past of extreme environments 12 00:00:40,957 --> 00:00:43,584 and extreme catastrophes. 13 00:00:43,710 --> 00:00:46,670 Over the course of nearly 5 billion years, 14 00:00:46,796 --> 00:00:49,089 it has been a changing world, 15 00:00:49,215 --> 00:00:51,091 a world of fire, 16 00:00:51,217 --> 00:00:53,260 a world of ice, 17 00:00:53,386 --> 00:00:56,096 one of raging seas 18 00:00:56,222 --> 00:00:59,475 and poisonous skies. 19 00:00:59,601 --> 00:01:02,144 The life-forms that now cling to its surface 20 00:01:02,270 --> 00:01:03,729 are the lucky survivors 21 00:01:03,855 --> 00:01:07,399 of a succession of deadly mass extinctions. 22 00:01:10,570 --> 00:01:12,446 Forjust over 200 years, 23 00:01:12,572 --> 00:01:15,282 determined scientists have explored the planet 24 00:01:15,408 --> 00:01:17,534 and unearthed its secrets. 25 00:01:17,660 --> 00:01:20,454 Their remarkable discoveries have led them to tell 26 00:01:20,580 --> 00:01:22,289 an incredible story, 27 00:01:22,415 --> 00:01:26,502 the story of "How The Earth Was Made." 28 00:01:35,804 --> 00:01:38,597 For thousands of years, humans had no knowledge 29 00:01:38,723 --> 00:01:41,683 of the true age and origin of the world. 30 00:01:41,810 --> 00:01:46,688 Butjust over 200 years ago, all this would change. 31 00:01:49,400 --> 00:01:52,319 Scotland, the Edinburgh coast: 32 00:01:52,445 --> 00:01:54,488 it was here, one day in 1 788, 33 00:01:54,614 --> 00:01:57,991 that the discovery of a small rocky outcrop 34 00:01:58,118 --> 00:02:01,620 would completely rewrite the history of the Earth. 35 00:02:11,631 --> 00:02:13,507 Geologist Geoffrey Boulton 36 00:02:13,633 --> 00:02:16,385 is on his way to the desolate Siccar Point, 37 00:02:16,511 --> 00:02:18,137 where this discovery was made 38 00:02:18,263 --> 00:02:22,266 by a maverick Scottish farmer, James Hutton. 39 00:02:24,435 --> 00:02:28,147 Hutton was to become the father of modern geology. 40 00:02:28,273 --> 00:02:30,232 - Hutton was a man who was enthusiastic 41 00:02:30,358 --> 00:02:33,360 in the pursuit of truth, a very inquiring mind. 42 00:02:33,486 --> 00:02:35,237 When he took over his father's farm, 43 00:02:35,363 --> 00:02:37,573 he saw, underneath the soils, rocks 44 00:02:37,699 --> 00:02:39,825 and wondered what these were. 45 00:02:39,951 --> 00:02:42,452 narrator: Hutton spent years obsessed with understanding 46 00:02:42,579 --> 00:02:44,496 how the rocks of the Earth were made. 47 00:02:44,622 --> 00:02:48,083 His intrepid field expeditions took him all over Scotland, 48 00:02:48,209 --> 00:02:51,378 and they led him to realize that extremely slow processes 49 00:02:51,504 --> 00:02:56,216 could create the rocks he saw from layers of sediment. 50 00:02:56,342 --> 00:02:58,385 - He rode miles and miles on his horse 51 00:02:58,511 --> 00:03:00,762 to go places where he thought he could find 52 00:03:00,889 --> 00:03:03,182 exciting geological experiences 53 00:03:03,308 --> 00:03:06,059 even though he suffered terribly from saddle sores. 54 00:03:06,186 --> 00:03:08,395 narrator: Hutton concluded that rocks could take 55 00:03:08,521 --> 00:03:10,981 hundreds of thousands of years to form. 56 00:03:11,107 --> 00:03:12,774 But his claims were speculative, 57 00:03:12,901 --> 00:03:14,651 and his radical ideas flew in the face 58 00:03:14,777 --> 00:03:18,113 of the accepted version of Earth history, 59 00:03:18,239 --> 00:03:21,617 provided by the church. 60 00:03:21,743 --> 00:03:23,952 For generations, the Christian church 61 00:03:24,078 --> 00:03:27,414 had been the sole authority on all creation, 62 00:03:27,540 --> 00:03:30,209 based on the book of Genesis. 63 00:03:32,879 --> 00:03:35,047 And using the biblical genealogies, 64 00:03:35,173 --> 00:03:37,549 church leaders were now confidently claiming 65 00:03:37,675 --> 00:03:42,387 they knew the exact age of the Earth itself. 66 00:03:42,513 --> 00:03:44,848 - Archbishop Ussher in the 1 7th century 67 00:03:44,974 --> 00:03:48,936 had calculated that the Earth was 6,000 years old, 68 00:03:49,062 --> 00:03:51,230 and indeed, he calculated that it was made 69 00:03:51,356 --> 00:03:53,607 on October the 14th in the afternoon. 70 00:03:53,733 --> 00:03:55,317 narrator: Hutton was convinced 71 00:03:55,443 --> 00:03:57,945 that the Earth had to be much older. 72 00:03:58,071 --> 00:04:02,366 And when his explorations led him to Siccar Point in 1 788, 73 00:04:02,492 --> 00:04:05,661 he would finally find the proof he was looking for 74 00:04:05,787 --> 00:04:09,206 in the unusual formation he discovered. 75 00:04:12,961 --> 00:04:15,754 - These rocks are notjust any old rocks. 76 00:04:15,880 --> 00:04:19,758 They're very special rocks, and the reason they're special 77 00:04:19,884 --> 00:04:24,304 is because of the story Hutton was able to tell from them. 78 00:04:24,430 --> 00:04:26,890 narrator: Here, two layered rock formations 79 00:04:27,016 --> 00:04:31,228 stand at right angles to each other. 80 00:04:31,354 --> 00:04:32,562 - He knew these rocks 81 00:04:32,689 --> 00:04:35,649 had once been laid down horizontally on the seafloor. 82 00:04:35,775 --> 00:04:38,026 They must then have been buried under great depth 83 00:04:38,152 --> 00:04:39,528 to recrystallize. 84 00:04:39,654 --> 00:04:43,031 They must then have been tilted on end by great Earth forces. 85 00:04:43,157 --> 00:04:45,534 Then they were eroded away and truncated. 86 00:04:45,660 --> 00:04:47,911 Then these rocks were deposited on top. 87 00:04:48,037 --> 00:04:51,373 And he realized that that would not take hundreds of years 88 00:04:51,499 --> 00:04:54,626 nor thousands of years but many millions of years. 89 00:04:56,045 --> 00:04:58,755 narrator: Hutton's discovery was a turning point. 90 00:04:58,881 --> 00:05:02,551 From that day forward, it was rock, not scripture, 91 00:05:02,677 --> 00:05:06,680 that would become the trusted guide to the distant past. 92 00:05:09,392 --> 00:05:11,310 And over the next two centuries, 93 00:05:11,436 --> 00:05:13,603 the study of rocks around the globe 94 00:05:13,730 --> 00:05:16,106 would lead to the awesome revelation 95 00:05:16,232 --> 00:05:19,109 that this blue-green planet 96 00:05:19,235 --> 00:05:22,404 has been on the most astounding journey... 97 00:05:24,991 --> 00:05:28,910 Ajourney that began in a world of fire. 98 00:05:34,125 --> 00:05:35,876 lt is now believed that the Earth 99 00:05:36,002 --> 00:05:39,504 was formed from collisions among the countless meteors 100 00:05:39,630 --> 00:05:42,632 that made up the early solar system. 101 00:05:47,513 --> 00:05:51,433 Back then, the surface was an ocean of molten rock 102 00:05:51,559 --> 00:05:53,685 miles deep. 103 00:05:56,356 --> 00:06:00,067 Temperatures exceeded 8,000 degrees Fahrenheit, 104 00:06:00,193 --> 00:06:03,362 similar to the surface of the sun. 105 00:06:07,867 --> 00:06:13,372 And huge meteorites rained down in a relentless bombardment. 106 00:06:24,258 --> 00:06:28,220 The man who first proposed this hellish origin for the planet 107 00:06:28,346 --> 00:06:31,473 was the Victorian scientist Lord Kelvin. 108 00:06:31,599 --> 00:06:34,017 A British expert in thermodynamics, 109 00:06:34,143 --> 00:06:40,107 Kelvin believed that the Earth was slowly cooling down. 110 00:06:40,233 --> 00:06:42,609 The fires of the planet's interior, 111 00:06:42,735 --> 00:06:44,778 visible in volcanic eruptions, 112 00:06:44,904 --> 00:06:49,199 suggested to him that the planet had once been completely molten. 113 00:06:51,411 --> 00:06:52,953 Kelvin used thermodynamics 114 00:06:53,079 --> 00:06:56,665 to calculate a new age for the Earth. 115 00:06:56,791 --> 00:06:58,625 He reasoned that the molten planet 116 00:06:58,751 --> 00:07:00,836 would need nearly 20 million years 117 00:07:00,962 --> 00:07:05,298 to cool to its present temperatures. 118 00:07:05,425 --> 00:07:07,884 Kelvin was correct about the Earth being molten 119 00:07:08,010 --> 00:07:09,928 but not about its age. 120 00:07:10,054 --> 00:07:12,889 His figure was a colossal underestimate. 121 00:07:14,475 --> 00:07:16,810 Like all 1 9th-century scientists, 122 00:07:16,936 --> 00:07:19,563 Kelvin was unaware of a key source of heat 123 00:07:19,689 --> 00:07:21,481 inside the early Earth 124 00:07:21,607 --> 00:07:25,402 that prevented the planet from cooling as he predicted: 125 00:07:25,528 --> 00:07:28,822 radioactivity. 126 00:07:28,948 --> 00:07:31,074 ln the early Earth, radioactive particles 127 00:07:31,200 --> 00:07:33,535 of uranium, thorium, and potassium 128 00:07:33,661 --> 00:07:35,996 were in huge abundance. 129 00:07:36,122 --> 00:07:38,790 The heat produced from the decay of these particles 130 00:07:38,916 --> 00:07:41,126 would keep the Earth extremely hot 131 00:07:41,252 --> 00:07:43,545 for an extremely long time. 132 00:07:43,671 --> 00:07:45,005 But although these particles 133 00:07:45,131 --> 00:07:47,215 confounded Kelvin's calculations, 134 00:07:47,341 --> 00:07:49,384 they would eventually prove the keys 135 00:07:49,510 --> 00:07:52,637 to unlocking the true age of the Earth. 136 00:07:54,807 --> 00:07:56,141 ln the 20th century, 137 00:07:56,267 --> 00:07:58,852 rare particles of surviving radioactive uranium 138 00:07:58,978 --> 00:08:00,061 were collected together 139 00:08:00,188 --> 00:08:02,856 to create the first atomic weapons. 140 00:08:02,982 --> 00:08:05,901 But scientists had earlier found a different application, 141 00:08:06,027 --> 00:08:10,405 using the radioactive particles to accurately date the planet. 142 00:08:11,991 --> 00:08:16,495 ln 1 91 1 , a gifted 21-year-old geology student, Arthur Holmes, 143 00:08:16,621 --> 00:08:18,622 used radiation to revolutionize 144 00:08:18,748 --> 00:08:22,042 our understanding of Earth history. 145 00:08:22,168 --> 00:08:23,543 After Holmes, 146 00:08:23,669 --> 00:08:25,795 geologists would talk in billions, 147 00:08:25,922 --> 00:08:28,048 not millions, of years. 148 00:08:28,174 --> 00:08:30,967 Radiometric dating was simple in principle. 149 00:08:31,093 --> 00:08:32,594 lt was based on the discovery 150 00:08:32,720 --> 00:08:35,305 that traces of the radioactive element uranium, 151 00:08:35,431 --> 00:08:37,349 found throughout the rocks of the Earth, 152 00:08:37,475 --> 00:08:41,686 decayed into another element, lead. 153 00:08:41,812 --> 00:08:44,481 Like sand trickling through an hourglass 154 00:08:44,607 --> 00:08:46,274 over hundreds of millions of years 155 00:08:46,400 --> 00:08:47,901 and at a steady rate, 156 00:08:48,027 --> 00:08:52,572 a sample of radioactive uranium will decay to lead. 157 00:08:52,698 --> 00:08:55,450 By measuring the proportion of uranium to lead 158 00:08:55,576 --> 00:08:58,036 in crystals trapped in ancient rocks, 159 00:08:58,162 --> 00:09:03,250 Holmes could accurately calculate their ages. 160 00:09:03,376 --> 00:09:06,211 Collecting data from samples from all over the world 161 00:09:06,337 --> 00:09:10,507 would be a lifetime's work. 162 00:09:10,633 --> 00:09:16,263 But as Holmes grew older, so did the Earth. 163 00:09:16,389 --> 00:09:20,600 lts calculated age extended first to 1 billion, 164 00:09:20,726 --> 00:09:23,228 then 3 billion, 165 00:09:23,354 --> 00:09:29,401 then finally to 4.5 billion years. 166 00:09:29,527 --> 00:09:31,820 Today 4.5 billion years 167 00:09:31,946 --> 00:09:36,825 is still the accepted age for the Earth. 168 00:09:36,951 --> 00:09:39,244 Time on this incredible scale 169 00:09:39,370 --> 00:09:41,705 is known to those in the business 170 00:09:41,831 --> 00:09:43,915 as deep time. 171 00:09:44,041 --> 00:09:46,793 - lt's difficult to imagine how vast deep time is. 172 00:09:46,919 --> 00:09:48,128 But think of it this way. 173 00:09:48,254 --> 00:09:49,713 That's a grain of sand. 174 00:09:49,839 --> 00:09:52,757 lf it represented a year, then the length of my finger 175 00:09:52,883 --> 00:09:55,176 would be equivalent to the whole of my lifetime. 176 00:09:55,303 --> 00:09:57,304 From the tip of my finger to my elbow 177 00:09:57,430 --> 00:09:59,598 would take us back to the pilgrim fathers. 178 00:09:59,724 --> 00:10:02,475 From here to the rocky island you see on the horizon 179 00:10:02,602 --> 00:10:04,978 would take us back to the age of the dinosaurs. 180 00:10:05,104 --> 00:10:07,564 And if we were to turn round and go to the equator, 181 00:10:07,690 --> 00:10:09,232 then it would be equivalent to going back 182 00:10:09,358 --> 00:10:13,194 to the beginning of the Earth 4 1/2 billion years ago. 183 00:10:16,282 --> 00:10:19,159 narrator: The search for the age of the Earth was over, 184 00:10:19,285 --> 00:10:22,245 and the results had opened a window on the past. 185 00:10:22,371 --> 00:10:23,580 For the first time, 186 00:10:23,706 --> 00:10:26,541 scientists could put rocks in the correct order, 187 00:10:26,667 --> 00:10:30,587 look deep into the Earth's past, and tell its story. 188 00:10:30,713 --> 00:10:33,173 They would discover evidence of an epic journey 189 00:10:33,299 --> 00:10:35,759 with many twists and turns. 190 00:10:35,885 --> 00:10:38,845 But the most significant step may well have been taken 191 00:10:38,971 --> 00:10:42,474 within just a few hundred million years of its birth, 192 00:10:42,600 --> 00:10:45,644 when the planet became a water world. 193 00:10:50,524 --> 00:10:54,694 4.5 billion years ago, the Earth was formed 194 00:10:54,820 --> 00:10:56,780 from the collisions of millions of meteors 195 00:10:56,906 --> 00:10:59,699 in the young solar system. 196 00:10:59,825 --> 00:11:02,243 Temperatures were so high 197 00:11:02,370 --> 00:11:05,997 that the planet's surface was a molten ocean. 198 00:11:06,123 --> 00:11:10,001 But even at that time, Earth was beginning to cool. 199 00:11:10,127 --> 00:11:12,337 The radioactivity that provided much of the heat 200 00:11:12,463 --> 00:11:14,714 was slowly declining, paving the way 201 00:11:14,840 --> 00:11:17,550 for the planet's first radical change, 202 00:11:17,677 --> 00:11:21,721 its transformation into a water world. 203 00:11:25,518 --> 00:11:29,270 The Barberton Hills, South Africa: 204 00:11:29,397 --> 00:11:31,398 this remote region is home 205 00:11:31,524 --> 00:11:34,526 to some of the oldest rocks on Earth. 206 00:11:36,737 --> 00:11:38,988 South African geologist Gary Stevens 207 00:11:39,115 --> 00:11:40,532 is on the lookout for some 208 00:11:40,658 --> 00:11:42,784 of these incredibly rare survivors 209 00:11:42,910 --> 00:11:45,787 from the first billion years of Earth history 210 00:11:45,913 --> 00:11:48,998 whose unique shape tells a story. 211 00:11:51,544 --> 00:11:53,086 - This area of South African geology, 212 00:11:53,212 --> 00:11:56,005 here on the eastern side of Mpumalanga, is critical 213 00:11:56,132 --> 00:12:00,468 for our understanding of early Earth processes. 214 00:12:00,594 --> 00:12:02,804 narrator: Gradual erosion along the trickling creek 215 00:12:02,930 --> 00:12:06,516 can occasionally expose these primordial rocks. 216 00:12:06,642 --> 00:12:09,144 - Here we have an interesting rock. 217 00:12:09,270 --> 00:12:10,979 The rounded shape of this rock over here 218 00:12:11,105 --> 00:12:13,022 is very different than the rounded shape 219 00:12:13,149 --> 00:12:17,402 of the rest of the rocks in this river. 220 00:12:17,528 --> 00:12:18,570 This is one of these 221 00:12:18,696 --> 00:12:22,115 3.5-billion-year-old pillow lavas. 222 00:12:22,241 --> 00:12:24,284 The rounded pillow shape in the rock 223 00:12:24,410 --> 00:12:26,286 is a result of the lava 224 00:12:26,412 --> 00:12:28,246 that formed underwater in an ocean 225 00:12:28,372 --> 00:12:31,958 approximately 3 1/2 billion years ago. 226 00:12:32,084 --> 00:12:34,377 narrator: Pillow lavas are created today 227 00:12:34,503 --> 00:12:36,212 off the coast of Hawaii, 228 00:12:36,338 --> 00:12:41,176 where volcanic vents erupt into the Pacific Ocean. 229 00:12:41,302 --> 00:12:44,345 This unique pillow shape is only formed 230 00:12:44,472 --> 00:12:49,058 when lava solidifies under deep water. 231 00:12:49,185 --> 00:12:52,937 All rocks found from the period 3.5 billion years ago 232 00:12:53,063 --> 00:12:55,148 have been pillow lavas. 233 00:12:55,274 --> 00:12:58,151 By 1 billion years into the planet's existence, 234 00:12:58,277 --> 00:12:59,778 water had taken over. 235 00:12:59,904 --> 00:13:02,655 But geologists believe that it had already been around 236 00:13:02,782 --> 00:13:05,116 a long, long time. 237 00:13:08,078 --> 00:13:11,456 4.4 billion years ago, 238 00:13:11,582 --> 00:13:15,418 the Earth was around 1 00 million years old. 239 00:13:21,759 --> 00:13:24,135 Meteors still crashed into the planet, 240 00:13:24,261 --> 00:13:28,181 but gradual cooling of the core had allowed most of the surface 241 00:13:28,307 --> 00:13:33,561 to solidify into a crust of dark volcanic rock. 242 00:13:38,067 --> 00:13:41,319 And even then, at this early stage, 243 00:13:41,445 --> 00:13:46,324 water was forming on the surface. 244 00:13:46,450 --> 00:13:49,702 No rocks now survive from this most early period, 245 00:13:49,829 --> 00:13:53,331 but tiny crystals of zircon do. 246 00:13:53,457 --> 00:13:56,209 Uranium-carrying zircon is one of the crystals 247 00:13:56,335 --> 00:13:58,044 that helped date the Earth. 248 00:13:58,170 --> 00:14:00,088 But these crystals can also retain 249 00:14:00,214 --> 00:14:03,216 the chemical fingerprints of water molecules, 250 00:14:03,342 --> 00:14:04,676 and these fingerprints 251 00:14:04,802 --> 00:14:08,012 are all over the most ancient zircons. 252 00:14:10,558 --> 00:14:13,017 But the origin of the majority of the planet's water 253 00:14:13,143 --> 00:14:14,978 remains a mystery. 254 00:14:15,104 --> 00:14:17,730 As the planet cooled, the surface rocks 255 00:14:17,857 --> 00:14:21,234 began spewing out tons of carbon dioxide. 256 00:14:21,360 --> 00:14:22,402 Some water vapor 257 00:14:22,528 --> 00:14:25,113 would have been vented during this process, 258 00:14:25,239 --> 00:14:27,323 but some believe it would not have been enough 259 00:14:27,449 --> 00:14:29,242 to cover the surface. 260 00:14:29,368 --> 00:14:31,286 - The rocks, the material that accreted 261 00:14:31,412 --> 00:14:32,579 to form the Earth itself, 262 00:14:32,705 --> 00:14:36,040 would have been too dry, too close to the really hot sun. 263 00:14:36,166 --> 00:14:38,293 We have this problem of trying to understand 264 00:14:38,419 --> 00:14:41,504 where our water world got all of its water. 265 00:14:41,630 --> 00:14:44,591 narrator: lmpact expert Dan Durda supports the theory 266 00:14:44,717 --> 00:14:47,468 that the source of most of the Earth's water 267 00:14:47,595 --> 00:14:49,345 was extraterrestrial. 268 00:14:49,471 --> 00:14:51,264 - The idea today is that the Earth's oceans 269 00:14:51,390 --> 00:14:53,266 arrived from above. 270 00:14:53,392 --> 00:14:54,726 They were brought in 271 00:14:54,852 --> 00:14:56,936 in the water-rich asteroids and comets 272 00:14:57,062 --> 00:14:59,147 which peppered the Earth during the tail-off 273 00:14:59,273 --> 00:15:01,608 in its accretionary process. 274 00:15:01,734 --> 00:15:04,777 What l have here is a piece of an actual meteorite. 275 00:15:04,904 --> 00:15:06,029 This is the material 276 00:15:06,155 --> 00:15:07,655 from which the Earth itself formed. 277 00:15:07,781 --> 00:15:09,115 This primitive little meteorite 278 00:15:09,241 --> 00:15:11,492 contains about 5% of water. 279 00:15:11,619 --> 00:15:13,953 lt's that water, in objects like this, 280 00:15:14,079 --> 00:15:16,915 that was delivered to the Earth to form the Earth's oceans. 281 00:15:17,041 --> 00:15:18,958 narrator: Scientists are divided on this, 282 00:15:19,084 --> 00:15:21,252 but wherever the water came from, 283 00:15:21,378 --> 00:15:22,545 when it did arrive, 284 00:15:22,671 --> 00:15:25,840 it changed the planet dramatically. 285 00:15:25,966 --> 00:15:28,176 As it evaporated off the surface, 286 00:15:28,302 --> 00:15:32,221 huge amounts of water vapor rose to join the carbon dioxide 287 00:15:32,348 --> 00:15:37,644 in the young atmosphere, forming thick blanketing clouds. 288 00:15:43,776 --> 00:15:45,902 This condensing water would trigger 289 00:15:46,028 --> 00:15:50,365 the greatest downpour the Earth would ever see. 290 00:15:50,491 --> 00:15:54,160 [thunder booming] 291 00:15:54,286 --> 00:15:56,913 As thunderstorms rocked the skies, 292 00:15:57,039 --> 00:16:01,668 the rain began to fall on the rocky surface below, 293 00:16:01,794 --> 00:16:03,795 and it kept on falling. 294 00:16:03,921 --> 00:16:05,213 [thunder booming] 295 00:16:05,339 --> 00:16:09,884 lt would rain for millions and millions 296 00:16:10,010 --> 00:16:12,345 and millions of years. 297 00:16:12,471 --> 00:16:16,808 The result would be a water world. 298 00:16:20,813 --> 00:16:23,272 4 billion years ago, 299 00:16:23,399 --> 00:16:27,360 the Earth was now 1/2 billion years old. 300 00:16:31,365 --> 00:16:36,369 Over 90% of its surface had become a vast ocean. 301 00:16:40,374 --> 00:16:44,460 Small volcanic islands poked out from the waves. 302 00:16:46,839 --> 00:16:49,382 The monstrous seas were iron-rich, 303 00:16:49,508 --> 00:16:52,135 making them an olive green color. 304 00:16:52,261 --> 00:16:55,471 Carbon dioxide filled the skies so thickly 305 00:16:55,597 --> 00:16:57,223 that they appeared red. 306 00:16:57,349 --> 00:17:00,226 The dense atmosphere produced enough pressure 307 00:17:00,352 --> 00:17:03,813 to crush a human body flat. 308 00:17:07,484 --> 00:17:09,610 And it was hot. 309 00:17:09,737 --> 00:17:15,033 Temperatures exceeded 200 degrees Fahrenheit. 310 00:17:15,159 --> 00:17:18,578 This toxic, hostile water world would remain 311 00:17:18,704 --> 00:17:21,748 for another 1/2 billion years. 312 00:17:21,874 --> 00:17:26,127 But dramatic transformations were on their way. 313 00:17:26,253 --> 00:17:27,920 Renewed volcanic activity 314 00:17:28,047 --> 00:17:30,590 would trigger the construction of the continents 315 00:17:30,716 --> 00:17:34,093 by creating a totally new kind of rock. 316 00:17:34,219 --> 00:17:38,264 Earth was about to become a granite planet. 317 00:17:41,518 --> 00:17:45,772 3.4 billion years ago, 318 00:17:45,898 --> 00:17:49,358 the Earth was just over a billion years old. 319 00:17:52,237 --> 00:17:55,740 Huge green oceans dominated. 320 00:18:05,125 --> 00:18:07,126 None of the crumbling volcanic islands 321 00:18:07,252 --> 00:18:08,628 dotting the surface 322 00:18:08,754 --> 00:18:11,798 survived the punishing seas for long. 323 00:18:11,924 --> 00:18:14,842 But everything was about to change. 324 00:18:14,968 --> 00:18:17,804 An upsurge in undersea volcanic activity 325 00:18:17,930 --> 00:18:20,640 was about to create a tougher type of rock 326 00:18:20,766 --> 00:18:24,102 and give birth to the continents. 327 00:18:24,228 --> 00:18:26,187 ln remote areas of the globe, 328 00:18:26,313 --> 00:18:29,107 the primeval cores of these first continents 329 00:18:29,233 --> 00:18:32,527 have been exposed. 330 00:18:32,653 --> 00:18:34,946 South Africa: 331 00:18:35,072 --> 00:18:37,156 geologist Gary Stevens is climbing 332 00:18:37,282 --> 00:18:42,453 on some of the oldest continental rock on Earth. 333 00:18:42,579 --> 00:18:45,164 These rocks are special. 334 00:18:45,290 --> 00:18:47,208 - We're standing here on an ancient granite. 335 00:18:47,334 --> 00:18:49,335 This granite forms the nucleus 336 00:18:49,461 --> 00:18:52,296 of one of the world's oldest continents. 337 00:18:52,422 --> 00:18:53,756 And we can see it here 338 00:18:53,882 --> 00:18:56,175 in the Barberton area in South Africa. 339 00:18:56,301 --> 00:18:58,219 narrator: These eroded outcrops of rock 340 00:18:58,345 --> 00:18:59,428 are the visible peaks 341 00:18:59,555 --> 00:19:02,348 of what is known as the Kaapvaal craton, 342 00:19:02,474 --> 00:19:04,976 a titanic mass of ancient granite 343 00:19:05,102 --> 00:19:06,727 underlying southern Africa, 344 00:19:06,854 --> 00:19:09,355 a remnant of the early Earth. 345 00:19:09,481 --> 00:19:12,024 3.5 billion years ago, 346 00:19:12,151 --> 00:19:15,319 granite was appearing everywhere. 347 00:19:15,445 --> 00:19:17,822 An upsurge of volcanism had fractured 348 00:19:17,948 --> 00:19:21,409 the crust of the Earth underneath the vast oceans, 349 00:19:21,535 --> 00:19:23,911 allowing water to plunge into the cracks 350 00:19:24,037 --> 00:19:27,039 alongside the molten lavas. 351 00:19:27,166 --> 00:19:30,293 The mixture of superheated water and basaltic lava 352 00:19:30,419 --> 00:19:33,754 produced the new rock, granite. 353 00:19:33,881 --> 00:19:35,506 lt rose from the depths 354 00:19:35,632 --> 00:19:39,135 to form the first true continental crust. 355 00:19:39,261 --> 00:19:41,387 - This is why granite is special and important. 356 00:19:41,513 --> 00:19:42,889 lt's light. 357 00:19:43,015 --> 00:19:46,058 This rock, granitic rock, has a much lower density 358 00:19:46,185 --> 00:19:48,519 than this rock, a basaltic rock. 359 00:19:48,645 --> 00:19:51,147 The difference in density between these two rocks 360 00:19:51,273 --> 00:19:53,191 is greater than the difference in density 361 00:19:53,317 --> 00:19:54,859 between water and air. 362 00:19:54,985 --> 00:19:57,570 This rock would be typical for oceanic crustal material. 363 00:19:57,696 --> 00:19:59,864 This is typical of the continents. 364 00:19:59,990 --> 00:20:01,741 Continents are light and buoyant, 365 00:20:01,867 --> 00:20:04,702 oceanic crust denser and heavier. 366 00:20:04,828 --> 00:20:07,413 lt literally floats on the mantle. 367 00:20:10,042 --> 00:20:11,876 narrator: Granite crust was not only light. 368 00:20:12,002 --> 00:20:14,212 lt was tough, 369 00:20:14,338 --> 00:20:18,549 tough enough to withstand the erosive power of the oceans. 370 00:20:24,181 --> 00:20:26,307 For the next couple of billion years, 371 00:20:26,433 --> 00:20:27,642 slowly but surely, 372 00:20:27,768 --> 00:20:32,772 the granitoid proto-continents grew larger. 373 00:20:32,898 --> 00:20:36,692 On different parts of the globe, granite crust appeared 374 00:20:36,818 --> 00:20:38,653 that would one day form the hearts 375 00:20:38,779 --> 00:20:41,781 of the major land masses. 376 00:20:41,907 --> 00:20:45,618 The dominance of the oceans was over. 377 00:20:45,744 --> 00:20:48,621 The continents had arrived. 378 00:20:51,166 --> 00:20:53,876 The slow expansion of the granite proto-continents 379 00:20:54,002 --> 00:20:57,505 was to change more than just the appearance of the planet. 380 00:20:57,631 --> 00:20:59,090 The shallow coastlines 381 00:20:59,216 --> 00:21:01,300 would bring life to the sunlit surface 382 00:21:01,426 --> 00:21:05,680 and help trigger the production of oxygen. 383 00:21:05,806 --> 00:21:08,266 Almost since the arrival of the first oceans, 384 00:21:08,392 --> 00:21:11,227 it is believed that primitive single-celled life-forms 385 00:21:11,353 --> 00:21:13,771 had appeared deep beneath the waves, 386 00:21:13,897 --> 00:21:17,900 living off the heat produced by the subsea volcanic fissures. 387 00:21:18,026 --> 00:21:21,362 But now they were evolving and spreading upwards. 388 00:21:21,488 --> 00:21:24,657 On the continental coasts, an organism was appearing 389 00:21:24,783 --> 00:21:28,035 that was to transform the planet: 390 00:21:28,161 --> 00:21:30,788 the stromatolite. 391 00:21:30,914 --> 00:21:34,000 The stromatolite would live off sunlight, 392 00:21:34,126 --> 00:21:38,629 and it would fill the atmosphere with oxygen. 393 00:21:40,215 --> 00:21:44,385 This primeval organism can still be found today. 394 00:21:53,103 --> 00:21:55,354 Western Australia: 395 00:21:55,480 --> 00:21:58,190 Martin van Kranendonk is over 1 00 miles 396 00:21:58,317 --> 00:21:59,692 from the nearest town, 397 00:21:59,818 --> 00:22:03,821 heading across the outback to a remote beach. 398 00:22:03,947 --> 00:22:05,114 - We're going down this track 399 00:22:05,240 --> 00:22:07,033 to one of the most unique places in the world, 400 00:22:07,159 --> 00:22:08,784 where you've got living stromatolites 401 00:22:08,910 --> 00:22:12,663 on the shoreline here at Shark Bay. 402 00:22:12,789 --> 00:22:15,583 narrator: On the narrow, sandy coast of Shark Bay, 403 00:22:15,709 --> 00:22:20,463 a multitude of stromatolites fill the tidal shallows. 404 00:22:23,592 --> 00:22:26,010 Each of these unusual rocky mounds 405 00:22:26,136 --> 00:22:31,515 are up to one foot across and two feet high. 406 00:22:31,641 --> 00:22:33,893 lt was only in the 1 950s 407 00:22:34,019 --> 00:22:37,772 that the importance of Shark Bay was realized. 408 00:22:37,898 --> 00:22:40,232 Following trips to this remote site, 409 00:22:40,359 --> 00:22:42,568 Australian geologist Phillip Playford 410 00:22:42,694 --> 00:22:46,447 was the first to discover how stromatolites formed. 411 00:22:46,573 --> 00:22:49,450 Playford identified a rare bacterial algae 412 00:22:49,576 --> 00:22:52,495 found in a slimy film coating their surface 413 00:22:52,621 --> 00:22:55,998 as the creator of the mounds themselves. 414 00:22:56,124 --> 00:22:57,833 - Stromatolites are made up 415 00:22:57,959 --> 00:23:00,878 of very thin layers of microorganisms 416 00:23:01,004 --> 00:23:04,423 that build up slowly, layer by layer, 417 00:23:04,549 --> 00:23:05,841 year by year, 418 00:23:05,967 --> 00:23:08,636 as they use light energy to gain their food, 419 00:23:08,762 --> 00:23:11,972 and as a waste product, they precipitate rock. 420 00:23:12,099 --> 00:23:14,600 narrator: Other geologists recognized the significance 421 00:23:14,726 --> 00:23:16,352 of Playford's findings. 422 00:23:16,478 --> 00:23:19,063 Patterns they had seen in rocks billions of years old 423 00:23:19,189 --> 00:23:22,108 were in fact fossilized stromatolites. 424 00:23:22,234 --> 00:23:23,401 Playford's discovery 425 00:23:23,527 --> 00:23:26,112 had sparked off a fossil revolution. 426 00:23:26,238 --> 00:23:28,781 - Once people knew that these kind of structures 427 00:23:28,907 --> 00:23:30,699 were made by living organisms, 428 00:23:30,826 --> 00:23:32,535 they went back into the rock record 429 00:23:32,661 --> 00:23:35,079 and found that they found the same kinds of structures 430 00:23:35,205 --> 00:23:38,457 and therefore could deduce that life occupied planet Earth 431 00:23:38,583 --> 00:23:40,334 3 1/2 billion years ago. 432 00:23:40,460 --> 00:23:44,296 These are really the ancestors of everything on Earth. 433 00:23:44,423 --> 00:23:47,258 We're actually looking at our great-great-great-great-great- 434 00:23:47,384 --> 00:23:49,927 great-great-great-great- grandmothers and grandfathers. 435 00:23:52,931 --> 00:23:56,642 narrator: The rock record shows that by 2.5 billion years ago, 436 00:23:56,768 --> 00:23:59,728 stromatolites were blossoming globally. 437 00:23:59,855 --> 00:24:03,899 All beaches on Earth would've resembled Shark Bay. 438 00:24:09,281 --> 00:24:12,158 And as stromatolites filled the shallows, 439 00:24:12,284 --> 00:24:17,288 they began to fill the atmosphere with oxygen. 440 00:24:17,414 --> 00:24:18,706 - Planet Earth in the solar system 441 00:24:18,832 --> 00:24:20,666 is the only planet that has an atmosphere 442 00:24:20,792 --> 00:24:23,335 composed of a large amount of oxygen. 443 00:24:23,462 --> 00:24:25,629 Geoscientists think that that oxygen 444 00:24:25,755 --> 00:24:29,341 came only from the reaction of stromatolites. 445 00:24:29,468 --> 00:24:33,179 narrator: The algae turned sunlight into oxygen, 446 00:24:33,305 --> 00:24:37,683 a process known as photosynthesis. 447 00:24:37,809 --> 00:24:39,768 Over a period of 2 billion years, 448 00:24:39,895 --> 00:24:42,021 countless generations of stromatolites 449 00:24:42,147 --> 00:24:46,358 pumped out over 20 million billion tons of oxygen. 450 00:24:46,485 --> 00:24:49,195 At first, the gas dissolved into the oceans, 451 00:24:49,321 --> 00:24:52,740 where it rusted out billions of tons of iron. 452 00:24:52,866 --> 00:24:56,035 But eventually, it would also fill the atmosphere 453 00:24:56,161 --> 00:24:58,704 and transform the planet. 454 00:24:58,830 --> 00:25:03,709 The planet's very appearance was dramatically altered. 455 00:25:03,835 --> 00:25:09,006 As the iron left the oceans, they changed from green to blue. 456 00:25:09,132 --> 00:25:11,175 When the oxygen moved on to the atmosphere, 457 00:25:11,301 --> 00:25:14,386 it diluted the remaining thick carbon dioxide 458 00:25:14,513 --> 00:25:17,014 and cleared the air. 459 00:25:26,358 --> 00:25:30,277 After nearly 2 billion years of oxygenation, 460 00:25:30,403 --> 00:25:33,531 the blue planet was born. 461 00:25:37,035 --> 00:25:39,078 The Earth now had its blue oceans 462 00:25:39,204 --> 00:25:41,205 and its blue sky. 463 00:25:47,504 --> 00:25:50,047 Relics of this great transformative period 464 00:25:50,173 --> 00:25:54,927 survive today in immense layers of iron-rich sediment 465 00:25:55,053 --> 00:25:56,095 originally deposited 466 00:25:56,221 --> 00:25:59,932 on the floors of the ancient oceans. 467 00:26:00,058 --> 00:26:01,517 Scattered all throughout the globe, 468 00:26:01,643 --> 00:26:04,520 the banded iron formations, as they are known, 469 00:26:04,646 --> 00:26:08,148 are vital for today's economies. 470 00:26:08,275 --> 00:26:13,112 They are the major source of all the iron mined today. 471 00:26:14,990 --> 00:26:19,868 Following its oxygenation, the Earth was more recognizable. 472 00:26:19,995 --> 00:26:22,621 But before it would become the planet we know, 473 00:26:22,747 --> 00:26:26,375 a new cycle of cataclysmic events would take place. 474 00:26:26,501 --> 00:26:28,294 Over the next billion years, 475 00:26:28,420 --> 00:26:31,463 deep movements would wrench apart the crust, 476 00:26:31,590 --> 00:26:35,092 and life, which had just begun to make its mark, 477 00:26:35,218 --> 00:26:37,928 would face its toughest test yet. 478 00:26:49,274 --> 00:26:52,484 1 .5 billion years ago, 479 00:26:52,611 --> 00:26:56,739 planet Earth was almost 3 billion years old. 480 00:26:56,865 --> 00:26:59,241 For the first time in its history, 481 00:26:59,367 --> 00:27:02,828 it was beginning to resemble the planet we know. 482 00:27:02,954 --> 00:27:06,749 Newly arrived oxygen had turned the oceans blue, 483 00:27:06,875 --> 00:27:08,334 and the continents had grown 484 00:27:08,460 --> 00:27:11,629 to cover nearly 1/4 of the surface. 485 00:27:11,755 --> 00:27:14,381 But their expansion was not over, 486 00:27:14,507 --> 00:27:17,468 and beneath the oceans, deep forces were at work, 487 00:27:17,594 --> 00:27:19,928 rearranging their positions. 488 00:27:20,055 --> 00:27:24,558 lmperceptibly, the continents were on the move. 489 00:27:30,482 --> 00:27:34,151 Mark McMenamin is an expert in plate tectonics, 490 00:27:34,277 --> 00:27:37,029 the study of continental movement. 491 00:27:37,155 --> 00:27:42,660 Until the 1 960s, this was radical science. 492 00:27:44,954 --> 00:27:47,498 - ln the 1 9th and early 20th century, 493 00:27:47,624 --> 00:27:51,919 the consensus view was that the continents were fixed. 494 00:27:52,045 --> 00:27:53,545 All geology was local, 495 00:27:53,672 --> 00:27:56,340 and the continents stay in one place. 496 00:27:56,466 --> 00:27:59,885 narrator: But problems for this view had been mounting. 497 00:28:00,011 --> 00:28:01,553 One of the greatest mysteries 498 00:28:01,680 --> 00:28:05,891 was the geographic position of certain fossils. 499 00:28:06,017 --> 00:28:08,435 - Trilobites like the one on my left here 500 00:28:08,561 --> 00:28:11,689 belong to the genus Paradoxides. 501 00:28:11,815 --> 00:28:14,400 narrator: The Paradoxides really was a paradox. 502 00:28:14,526 --> 00:28:17,695 lt was a freshwater creature with a curious distribution. 503 00:28:17,821 --> 00:28:20,030 - This trilobite is found 504 00:28:20,156 --> 00:28:23,117 in the eastern part of North America... 505 00:28:23,243 --> 00:28:24,910 - And also in Britain, 506 00:28:25,036 --> 00:28:28,539 on the other side of the Atlantic Ocean. 507 00:28:28,665 --> 00:28:30,249 narrator: The freshwater Paradoxides 508 00:28:30,375 --> 00:28:33,961 could not have swum the vast salty ocean. 509 00:28:36,047 --> 00:28:37,423 And they were not the only fossils 510 00:28:37,549 --> 00:28:41,427 showing bizarre intercontinental distribution. 511 00:28:41,553 --> 00:28:44,888 Geologists struggled for an explanation. 512 00:28:46,725 --> 00:28:51,603 ln 1 912, a radical new theory would emerge from Greenland 513 00:28:51,730 --> 00:28:54,106 that would lay the foundations for plate tectonics 514 00:28:54,232 --> 00:28:58,861 and shake Earth science to its foundations. 515 00:28:58,987 --> 00:29:00,487 The new theory was put forward 516 00:29:00,613 --> 00:29:03,991 by a German weather scientist, Alfred Wegener, 517 00:29:04,117 --> 00:29:06,034 a man who had spent much of his career 518 00:29:06,161 --> 00:29:10,414 conducting atmospheric research in Greenland's frozen wastes. 519 00:29:10,540 --> 00:29:12,291 But Wegener had always been fascinated 520 00:29:12,417 --> 00:29:15,043 by the geologist's fossil paradox, 521 00:29:15,170 --> 00:29:17,045 and he boldly claimed that the answer 522 00:29:17,172 --> 00:29:19,339 was staring them in the face. 523 00:29:19,466 --> 00:29:22,968 - Ever since accurate world maps were available, 524 00:29:23,094 --> 00:29:25,137 schoolchildren and others have pointed out the fit 525 00:29:25,263 --> 00:29:27,973 between the east coast of South America 526 00:29:28,099 --> 00:29:29,641 and the west coast of Africa. 527 00:29:29,768 --> 00:29:33,395 And this was always dismissed in reputable scientific circles 528 00:29:33,521 --> 00:29:36,315 as just a coincidence of no meaning. 529 00:29:36,441 --> 00:29:37,983 And so many disappointed children 530 00:29:38,109 --> 00:29:41,779 were turned away and told that their idea was wrong. 531 00:29:41,905 --> 00:29:43,906 narrator: Wegener proposed that the continents 532 00:29:44,032 --> 00:29:46,450 had indeed once been joined together 533 00:29:46,576 --> 00:29:49,495 and had subsequently drifted apart. 534 00:29:52,207 --> 00:29:54,208 His observations in Greenland convinced him 535 00:29:54,334 --> 00:29:58,879 this continental drift was possible. 536 00:29:59,005 --> 00:30:02,424 - l think that his inspiration was meteorological. 537 00:30:02,550 --> 00:30:05,010 Perhaps he saw breakup of ice floes 538 00:30:05,136 --> 00:30:08,222 and made what we would call an extrapolation 539 00:30:08,348 --> 00:30:13,310 to the hard rock part of the planet. 540 00:30:13,436 --> 00:30:15,229 narrator: But few geologists could accept 541 00:30:15,355 --> 00:30:18,899 the radical theories of a mere meteorologist. 542 00:30:19,025 --> 00:30:22,486 - There was complete rejection of what Wegener was saying. 543 00:30:22,612 --> 00:30:27,032 This is a tall order, to take a gigantic continent 544 00:30:27,158 --> 00:30:29,368 and shove it through the ocean floor 545 00:30:29,494 --> 00:30:31,578 to get it halfway across the globe. 546 00:30:34,958 --> 00:30:36,333 narrator: Throughout his life, 547 00:30:36,459 --> 00:30:39,711 Wegener fought to gain evidence for his theory. 548 00:30:39,838 --> 00:30:44,383 But his brave attempts eventually led to his demise. 549 00:30:44,509 --> 00:30:49,096 ln 1 930, his last expedition to Greenland ended in tragedy 550 00:30:49,222 --> 00:30:53,433 when he lost his way in a snowstorm. 551 00:30:53,560 --> 00:30:56,395 - ln an icy situation on a glacier, 552 00:30:56,521 --> 00:30:59,898 it's difficult to find your way. 553 00:31:00,024 --> 00:31:02,860 Separated from both his base camp 554 00:31:02,986 --> 00:31:05,362 and the other members of his expedition, 555 00:31:05,488 --> 00:31:09,199 he basically got lost and died of exposure. 556 00:31:11,244 --> 00:31:13,036 narrator: Wegener was dead, 557 00:31:13,162 --> 00:31:17,374 but his theory of continental drift lived on. 558 00:31:21,212 --> 00:31:23,589 The breakthrough came after the U.S. Navy 559 00:31:23,715 --> 00:31:26,466 produced a global map of the ocean floor, 560 00:31:26,593 --> 00:31:28,927 originally commissioned for submarine warfare 561 00:31:29,053 --> 00:31:30,762 during World War ll. 562 00:31:30,889 --> 00:31:32,306 [sonar pinging] 563 00:31:32,432 --> 00:31:39,146 This detailed map revealed one of the Earth's greatest secrets: 564 00:31:39,272 --> 00:31:41,857 the fractured network of submarine mountains, 565 00:31:41,983 --> 00:31:44,109 volcanic rifts, and trenches 566 00:31:44,235 --> 00:31:49,114 that split the oceans into enormous plates of crust. 567 00:31:49,240 --> 00:31:51,366 These plates would be the building blocks 568 00:31:51,492 --> 00:31:54,620 for the new science of plate tectonics. 569 00:31:54,746 --> 00:31:57,289 The rifts and trenches would provide a solution 570 00:31:57,415 --> 00:31:59,291 to how continents drift 571 00:31:59,417 --> 00:32:05,213 by proving that the ocean floors are continuously being recycled. 572 00:32:05,340 --> 00:32:08,383 - Plate tectonics is completely driven 573 00:32:08,509 --> 00:32:14,097 by the destruction of the old and the creation of the new 574 00:32:14,223 --> 00:32:15,682 narrator: Deep below the surface, 575 00:32:15,808 --> 00:32:19,311 mobile mantle rock is in continuous circular motion, 576 00:32:19,437 --> 00:32:21,313 following convection currents of heat 577 00:32:21,439 --> 00:32:24,316 generated deep within the planet. 578 00:32:24,442 --> 00:32:26,568 Where these currents rise, the rifts form, 579 00:32:26,694 --> 00:32:28,320 and the plates are pushed apart, 580 00:32:28,446 --> 00:32:32,282 with new ocean crust created in the gap. 581 00:32:32,408 --> 00:32:35,118 Where the mantle currents sink back down into the Earth, 582 00:32:35,244 --> 00:32:37,829 they drag old oceanic plate down with them 583 00:32:37,956 --> 00:32:39,665 towards the interior. 584 00:32:39,791 --> 00:32:43,835 As the ocean plate moves, so do the continents. 585 00:32:43,962 --> 00:32:49,007 - That oceanic plate drags the continent along with it. 586 00:32:49,133 --> 00:32:52,302 The process is like an escalator or a conveyor belt. 587 00:32:54,138 --> 00:32:56,014 narrator: The process of ocean creation 588 00:32:56,140 --> 00:32:58,100 is visible today on a rocky island 589 00:32:58,226 --> 00:33:00,560 in the middle of the Atlantic: 590 00:33:00,687 --> 00:33:02,562 lceland. 591 00:33:02,689 --> 00:33:05,524 lceland lies on the Mid-Atlantic Ridge, 592 00:33:05,650 --> 00:33:09,695 a 1 0,000-mile-long range of subsea volcanic mountains 593 00:33:09,821 --> 00:33:13,490 that mark one of the deep rifts in the Earth's crust. 594 00:33:15,785 --> 00:33:18,328 - lceland is really like a peak of this mountain chain. 595 00:33:18,454 --> 00:33:22,207 lt's like huge volcano sitting on top of it. 596 00:33:22,333 --> 00:33:23,917 narrator: Seismologist Páll Einarsson 597 00:33:24,043 --> 00:33:26,586 studies the volcanism of this remote island, 598 00:33:26,713 --> 00:33:30,882 volcanism that is helping to expand the Atlantic Ocean. 599 00:33:35,263 --> 00:33:38,682 Occasionally, an unusual type of volcanic eruption on lceland 600 00:33:38,808 --> 00:33:42,561 confirms the plate-tectonic process: 601 00:33:42,687 --> 00:33:45,147 a fissure eruption. 602 00:33:45,273 --> 00:33:48,275 A fissure eruption is a wall of fire. 603 00:33:48,401 --> 00:33:50,569 They can be 25 miles long 604 00:33:50,695 --> 00:33:53,822 and spew lava hundreds of feet into the air. 605 00:33:53,948 --> 00:33:55,574 - People fear eruptions. 606 00:33:55,700 --> 00:33:57,993 They respect the volcanoes. 607 00:34:04,208 --> 00:34:05,751 narrator: The fissures mark the path 608 00:34:05,877 --> 00:34:09,963 of the deep plate boundary that is creating the Atlantic. 609 00:34:10,089 --> 00:34:11,757 All across the island, 610 00:34:11,883 --> 00:34:14,092 running from northeast to southwest, 611 00:34:14,218 --> 00:34:17,262 are the remains of these fissure eruptions, 612 00:34:17,388 --> 00:34:21,767 scarring the rocky landscape with shallow canyons. 613 00:34:21,893 --> 00:34:25,896 These canyons are very slowly widening lceland. 614 00:34:31,694 --> 00:34:34,446 At their base, new crust is being created, 615 00:34:34,572 --> 00:34:37,949 pushing Europe and America apart. 616 00:34:38,076 --> 00:34:40,702 - So here we are located in the fissure 617 00:34:40,828 --> 00:34:42,704 between the two continental plates, 618 00:34:42,830 --> 00:34:44,998 the two crustal plates. 619 00:34:45,124 --> 00:34:47,959 Here on my left, we have the North America plate, 620 00:34:48,086 --> 00:34:51,463 and on the other side, we have Europe. 621 00:34:51,589 --> 00:34:54,091 This fissure here is in a lava flow 622 00:34:54,217 --> 00:34:56,593 that's only about 8,000 years old. 623 00:34:56,719 --> 00:34:57,844 So in 8,000 years, 624 00:34:57,970 --> 00:35:00,472 that's how much the two plates have moved. 625 00:35:00,598 --> 00:35:03,809 - The rate of continental drift 626 00:35:03,935 --> 00:35:07,979 averages about 2.5 centimeters per year, 627 00:35:08,106 --> 00:35:10,649 the rate at which fingernails typically grow. 628 00:35:10,775 --> 00:35:14,111 narrator: 2.5 centimeters, one inch per year, 629 00:35:14,237 --> 00:35:16,404 means that in one human lifetime, 630 00:35:16,531 --> 00:35:20,534 America and Europe will move just six feet further apart. 631 00:35:22,578 --> 00:35:25,831 But over millions of years, this speed of movement 632 00:35:25,957 --> 00:35:28,542 was enough to shift the continents 633 00:35:28,668 --> 00:35:31,253 thousands of miles. 634 00:35:35,466 --> 00:35:37,843 Using plate tectonics as their guide, 635 00:35:37,969 --> 00:35:39,928 geologists such as Mark McMenamin 636 00:35:40,054 --> 00:35:41,972 have reconstructed the epic story 637 00:35:42,098 --> 00:35:44,683 of continental movement from the beginning. 638 00:35:44,809 --> 00:35:48,061 From samples taken from present-day continental margins, 639 00:35:48,187 --> 00:35:50,730 they've compared fossils and microfossils 640 00:35:50,857 --> 00:35:53,900 and matched up distinctive types of ancient rocks 641 00:35:54,026 --> 00:35:57,362 to reconstruct where the continents used to be. 642 00:35:57,488 --> 00:35:59,114 - lt's a tricky task. 643 00:35:59,240 --> 00:36:00,615 lt's kind of like Humpty Dumpty. 644 00:36:00,741 --> 00:36:02,200 You've got all of these pieces. 645 00:36:02,326 --> 00:36:04,661 You need to use whatever clues you can, 646 00:36:04,787 --> 00:36:06,746 whatever fingerprints you can, 647 00:36:06,873 --> 00:36:11,251 to put one continental margin against the other. 648 00:36:11,377 --> 00:36:12,961 narrator: They are now confident 649 00:36:13,087 --> 00:36:15,255 that they can trace the movement of the continents 650 00:36:15,381 --> 00:36:18,466 back over a billion years 651 00:36:18,593 --> 00:36:21,511 to a time of a mass continental collision. 652 00:36:25,183 --> 00:36:27,809 As the oceans between them were swallowed up, 653 00:36:27,935 --> 00:36:30,437 the large land masses drew together 654 00:36:30,563 --> 00:36:35,692 in what was to become a supercontinent, Rodinia. 655 00:36:39,405 --> 00:36:41,907 lt is believed that Canada and the U.S.A. 656 00:36:42,033 --> 00:36:46,661 formed the supercontinent's heart, 657 00:36:46,787 --> 00:36:50,540 with other continents bunched around them. 658 00:36:53,002 --> 00:36:57,923 But Rodinia was unlike any continent seen today. 659 00:36:58,049 --> 00:37:02,385 lt was a desolate, lifeless place. 660 00:37:02,511 --> 00:37:04,804 - lt would've been very much like being in the desert. 661 00:37:04,931 --> 00:37:07,599 lt would've been similar to parts of the Sahara, 662 00:37:07,725 --> 00:37:09,267 Death Valley. 663 00:37:09,393 --> 00:37:11,937 There would have been no plants, no forests, 664 00:37:12,063 --> 00:37:14,397 no grasslands. 665 00:37:17,235 --> 00:37:20,862 Rodinia would have been a barren continent. 666 00:37:28,120 --> 00:37:30,413 narrator: Rodinia may have been lifeless, 667 00:37:30,539 --> 00:37:32,874 but it was to have a profound effect 668 00:37:33,000 --> 00:37:35,502 on life in the oceans. 669 00:37:35,628 --> 00:37:37,420 ln the oxygenated waters, 670 00:37:37,546 --> 00:37:39,297 primitive life-forms were blooming 671 00:37:39,423 --> 00:37:43,426 alongside the stromatolites. 672 00:37:43,552 --> 00:37:45,971 But the huge supercontinent was about to give them 673 00:37:46,097 --> 00:37:48,848 a tremendous shock. 674 00:37:48,975 --> 00:37:51,643 Rodinia was to trigger what is now known 675 00:37:51,769 --> 00:37:53,687 as "snowball Earth," 676 00:37:53,813 --> 00:37:58,650 the biggest freeze the world has ever seen. 677 00:37:58,776 --> 00:38:02,404 By around 700 million years ago, Rodinia's position 678 00:38:02,530 --> 00:38:04,948 was blocking the currents that brought warm water 679 00:38:05,074 --> 00:38:07,200 from the equator to the poles. 680 00:38:07,326 --> 00:38:10,996 Without this heat, the polar regions froze. 681 00:38:11,122 --> 00:38:13,790 The resulting ice reflected more of the sun's rays 682 00:38:13,916 --> 00:38:15,667 away from the Earth, 683 00:38:15,793 --> 00:38:17,877 and in a catastrophic snowballing effect, 684 00:38:18,004 --> 00:38:19,879 temperatures dropped still further, 685 00:38:20,006 --> 00:38:23,008 and the ice advanced to cover the Earth. 686 00:38:28,431 --> 00:38:32,350 Surface temperatures fell below minus 40 degrees. 687 00:38:32,476 --> 00:38:35,353 The oceans were covered in an ice sheet 688 00:38:35,479 --> 00:38:38,023 almost a mile deep. 689 00:38:38,149 --> 00:38:41,526 The only life on Earth, marine bacterias and algae, 690 00:38:41,652 --> 00:38:45,238 were trapped beneath in the darkness. 691 00:38:45,364 --> 00:38:48,366 The result was disaster. 692 00:38:48,492 --> 00:38:50,869 All but a tiny fraction of organisms 693 00:38:50,995 --> 00:38:53,705 were driven to extinction. 694 00:38:53,831 --> 00:38:57,167 The whole planet was dying. 695 00:39:06,344 --> 00:39:12,223 650 million years ago, climate changes triggered 696 00:39:12,350 --> 00:39:15,435 by the formation of the supercontinent Rodinia 697 00:39:15,561 --> 00:39:17,145 had left the surface of the Earth 698 00:39:17,271 --> 00:39:21,483 covered with a sheet of ice one mile thick. 699 00:39:21,609 --> 00:39:26,863 Temperatures hovered below minus 40 degrees Fahrenheit. 700 00:39:26,989 --> 00:39:30,241 Marine organisms, the only life on the planet, 701 00:39:30,368 --> 00:39:32,660 had almost been wiped out. 702 00:39:32,787 --> 00:39:37,540 The future of life on Earth hung in the balance. 703 00:39:43,756 --> 00:39:45,256 But beneath the ice, 704 00:39:45,383 --> 00:39:50,178 the supercontinent was in turmoil. 705 00:39:50,304 --> 00:39:54,766 Vast volcanic eruptions were splitting Rodinia apart. 706 00:39:54,892 --> 00:39:57,102 - lt's thought that the accumulation of heat 707 00:39:57,228 --> 00:39:58,853 at the base of the supercontinent 708 00:39:58,979 --> 00:40:02,524 is what eventually leads to its undoing. 709 00:40:02,650 --> 00:40:05,610 lt's like putting a blanket over the Earth. 710 00:40:05,736 --> 00:40:07,904 The heat that's generated in the Earth's interior 711 00:40:08,030 --> 00:40:10,490 will accumulate underneath that blanket. 712 00:40:10,616 --> 00:40:14,619 narrator: The heat would spell the end of the snowball. 713 00:40:14,745 --> 00:40:16,371 As Rodinia ruptured, 714 00:40:16,497 --> 00:40:18,790 carbon dioxide released by the eruptions 715 00:40:18,916 --> 00:40:21,960 created a temporary greenhouse effect. 716 00:40:22,086 --> 00:40:25,672 The ice sheets drew back. 717 00:40:25,798 --> 00:40:30,927 Rodinia had broken into giant fragments. 718 00:40:31,053 --> 00:40:37,142 And the icy grip on life was broken. 719 00:40:37,268 --> 00:40:40,520 As shallow seas opened up in Rodinia's wake 720 00:40:40,646 --> 00:40:42,981 and oxygen levels increased, 721 00:40:43,107 --> 00:40:44,858 the primitive organisms were free 722 00:40:44,984 --> 00:40:48,987 to take their next great step forward. 723 00:40:49,113 --> 00:40:54,409 They would become complex and a lot more dangerous. 724 00:40:57,455 --> 00:40:59,831 The Canadian Rockies: 725 00:40:59,957 --> 00:41:02,667 these remote mountains are home to a rare record 726 00:41:02,793 --> 00:41:05,712 of this key event in the evolution of life, 727 00:41:05,838 --> 00:41:09,090 the so-called Cambrian explosion. 728 00:41:09,216 --> 00:41:11,301 - For the first time in the history of life on Earth, 729 00:41:11,427 --> 00:41:13,470 we have some of the highest oxygen levels 730 00:41:13,596 --> 00:41:17,182 that we've had since the Earth was actually formed. 731 00:41:17,308 --> 00:41:18,475 Life bloomed. 732 00:41:18,601 --> 00:41:21,352 We see animals unlike we've ever seen before. 733 00:41:21,479 --> 00:41:23,354 narrator: Paleontologist Paul McNeil 734 00:41:23,481 --> 00:41:25,857 is hiking up to a remote mountain quarry 735 00:41:25,983 --> 00:41:29,068 known as the Burgess Shale. 736 00:41:29,195 --> 00:41:31,488 The astonishing fossils in this quarry 737 00:41:31,614 --> 00:41:33,948 are a window on the world as it existed 738 00:41:34,074 --> 00:41:37,327 over 500 million years ago. 739 00:41:37,453 --> 00:41:38,620 - lf you surveyed all the people 740 00:41:38,746 --> 00:41:40,038 who study the history of life, 741 00:41:40,164 --> 00:41:41,539 you get almost unanimous agreement 742 00:41:41,665 --> 00:41:43,041 that this is one of the most important 743 00:41:43,167 --> 00:41:44,334 fossil sites in the world. 744 00:41:49,840 --> 00:41:51,883 narrator: The man who discovered the Burgess Shale 745 00:41:52,009 --> 00:41:55,094 was an American, Charles Doolittle Walcott, 746 00:41:55,221 --> 00:41:58,139 the president of the Smithsonian lnstitute. 747 00:41:58,265 --> 00:42:01,559 This fanatical fossil hunter, who was born into poverty, 748 00:42:01,685 --> 00:42:04,187 had lived the American dream. 749 00:42:04,313 --> 00:42:06,606 Armed only with a high school diploma, 750 00:42:06,732 --> 00:42:08,233 he had fought his way to the top 751 00:42:08,359 --> 00:42:11,945 of the American scientific establishment. 752 00:42:12,071 --> 00:42:15,406 But it was his tenacious fossil-hunting expeditions 753 00:42:15,533 --> 00:42:18,117 in the most remote mountains of North America 754 00:42:18,244 --> 00:42:22,372 that would lead to his most stunning achievement. 755 00:42:22,498 --> 00:42:24,249 - This is the actual location 756 00:42:24,375 --> 00:42:28,002 where Walcott first made his amazing discovery. 757 00:42:28,128 --> 00:42:32,006 As the legend goes, it was August 31 , 1 909, 758 00:42:32,132 --> 00:42:36,344 riding along this very trail with his wife in a snowstorm. 759 00:42:36,470 --> 00:42:39,430 And as they were riding along, a large slab of rock came down, 760 00:42:39,557 --> 00:42:42,392 blocked the trail, and they couldn't get by. 761 00:42:42,518 --> 00:42:45,395 Now, being a gentleman, as all paleontologists are, 762 00:42:45,521 --> 00:42:47,605 he immediately leapt off his horse, 763 00:42:47,731 --> 00:42:49,148 flipped over the slab of rock, 764 00:42:49,275 --> 00:42:52,235 and found an incredibly well-preserved fossil. 765 00:42:52,361 --> 00:42:53,653 lt was down on the trail. 766 00:42:53,779 --> 00:42:55,113 Where did it come from? 767 00:42:55,239 --> 00:42:57,365 Nowhere but up there. 768 00:42:57,491 --> 00:42:58,908 narrator: The source of the rockfall 769 00:42:59,034 --> 00:43:04,664 was a section of the cliff no more than 1 00 feet across, 770 00:43:04,790 --> 00:43:06,457 a small area that became 771 00:43:06,584 --> 00:43:10,378 the celebrated Burgess Shale quarry. 772 00:43:17,428 --> 00:43:19,637 Walcott, often aided by his own family, 773 00:43:19,763 --> 00:43:23,516 eventually extracted over 60,000 fossils. 774 00:43:23,642 --> 00:43:24,892 And since Walcott, 775 00:43:25,019 --> 00:43:27,312 a further 1 00,000 have been excavated 776 00:43:27,438 --> 00:43:31,190 from this uniquely rich cliff face. 777 00:43:31,317 --> 00:43:33,651 - Quarrying the rocks out of the mountain 778 00:43:33,777 --> 00:43:35,612 requires a tremendous amount of work, 779 00:43:35,738 --> 00:43:38,823 a lot of backbreaking labor. 780 00:43:38,949 --> 00:43:40,325 But it's also extremely exciting, 781 00:43:40,451 --> 00:43:42,285 because every time you split open a rock, 782 00:43:42,411 --> 00:43:43,995 you never know what you're gonna find. 783 00:43:44,121 --> 00:43:45,663 Most of the time, you find nothing, 784 00:43:45,789 --> 00:43:48,416 but every once in a while, you find a new animal, 785 00:43:48,542 --> 00:43:50,209 one that's never been seen before, 786 00:43:50,336 --> 00:43:52,503 one that's been revealed for the first time 787 00:43:52,630 --> 00:43:54,047 in 1/2 billion years. 788 00:43:54,173 --> 00:43:55,840 narrator: The thousands of fossils 789 00:43:55,966 --> 00:43:57,175 found in the Burgess Shale 790 00:43:57,301 --> 00:44:00,303 reveal that starting 500 million years ago, 791 00:44:00,429 --> 00:44:04,682 life exploded with staggering diversity and complexity. 792 00:44:04,808 --> 00:44:06,184 - The preservation of these fossils 793 00:44:06,310 --> 00:44:07,560 is actually incredible 794 00:44:07,686 --> 00:44:10,897 in that they're actually preserved in three dimensions. 795 00:44:11,023 --> 00:44:13,566 You can excavate through the fossils themselves, 796 00:44:13,692 --> 00:44:15,401 see the internal organs, 797 00:44:15,527 --> 00:44:19,238 remove the organs, see the digestive tract. 798 00:44:21,158 --> 00:44:23,534 This is fantastic preservation. 799 00:44:23,661 --> 00:44:25,411 Oh, look, it's starting to crack, 800 00:44:25,537 --> 00:44:28,998 and there goes a piece. 801 00:44:29,124 --> 00:44:33,336 What we have here is an actual anomalocaris. 802 00:44:33,462 --> 00:44:35,296 These guys were up to a meter in length. 803 00:44:35,422 --> 00:44:38,675 That actually made them the T. rex of the Cambrian. 804 00:44:46,475 --> 00:44:49,769 narrator: ln the Cambrian seas, the oxygen-rich shallow waters 805 00:44:49,895 --> 00:44:54,315 were teeming with complex organisms. 806 00:44:54,441 --> 00:44:57,026 And creatures were feeding not just on plants 807 00:44:57,152 --> 00:44:59,487 but on each other. 808 00:45:03,367 --> 00:45:05,535 - The Cambrian is actually one of the most special times 809 00:45:05,661 --> 00:45:06,786 in the history of life. 810 00:45:06,912 --> 00:45:08,996 We see more different types of animals 811 00:45:09,123 --> 00:45:11,582 than we see in the rest of the entire history 812 00:45:11,709 --> 00:45:13,626 of life on Earth. 813 00:45:13,752 --> 00:45:15,378 narrator: From this time onwards, 814 00:45:15,504 --> 00:45:18,965 with a biological arms race driving their evolution, 815 00:45:19,091 --> 00:45:22,093 creatures would become increasingly complex, 816 00:45:22,219 --> 00:45:25,263 with the development of hard shells, skeletons, 817 00:45:25,389 --> 00:45:29,684 eyes, and teeth. 818 00:45:29,810 --> 00:45:33,688 Modern animals had arrived on Earth. 819 00:45:40,654 --> 00:45:42,780 The high level of oxygen that had triggered 820 00:45:42,906 --> 00:45:46,117 this explosion of life in the seas 821 00:45:46,243 --> 00:45:48,327 was also making a final modification 822 00:45:48,454 --> 00:45:50,747 to the atmosphere. 823 00:45:50,873 --> 00:45:53,166 Over the next 1 00 million years, 824 00:45:53,292 --> 00:45:57,670 oxygen reached today's high levels, 825 00:45:57,796 --> 00:46:00,631 a level dense enough to allow an ozone layer 826 00:46:00,758 --> 00:46:04,469 to form in the upper atmosphere. 827 00:46:04,595 --> 00:46:10,600 This layer was to free life-forms from the oceans. 828 00:46:10,726 --> 00:46:13,102 Previously, powerful ultraviolet light 829 00:46:13,228 --> 00:46:17,148 would destroy any organism not protected by the water. 830 00:46:17,274 --> 00:46:22,320 Now the ozone layer would act as a UV shield. 831 00:46:29,620 --> 00:46:32,246 400 million years ago, 832 00:46:32,372 --> 00:46:36,501 the Earth is more than 4 billion years old. 833 00:46:36,627 --> 00:46:38,753 Over the next 1 00 million years, 834 00:46:38,879 --> 00:46:42,632 the continents would once again converge. 835 00:46:42,758 --> 00:46:45,760 And this time, thanks to the ozone shield, 836 00:46:45,886 --> 00:46:49,680 life was free to leave the oceans 837 00:46:49,807 --> 00:46:52,266 and conquer the land. 838 00:46:52,392 --> 00:46:57,104 Planet Earth had become a world of tropical swamps. 839 00:47:00,108 --> 00:47:06,072 South Georgia, U.S.A., the Okefenokee Swamp. 840 00:47:07,616 --> 00:47:09,367 - The Okefenokee is believed to be 841 00:47:09,493 --> 00:47:11,369 what we would call an analogue, 842 00:47:11,495 --> 00:47:13,371 a modern analogue, or an environment 843 00:47:13,497 --> 00:47:15,540 that's very similar to the wetlands 844 00:47:15,666 --> 00:47:19,585 that existed on Earth in the past. 845 00:47:19,711 --> 00:47:24,757 narrator: Fred Rich is an expert on prehistoric swampland. 846 00:47:26,468 --> 00:47:30,221 Geologists like him believe that this freshwater swamp 847 00:47:30,347 --> 00:47:32,723 closely mimics the surface of the continents 848 00:47:32,850 --> 00:47:34,892 300 million years ago 849 00:47:35,018 --> 00:47:39,021 in a period known as the Carboniferous. 850 00:47:39,147 --> 00:47:42,066 - The Carboniferous was an unusual time 851 00:47:42,192 --> 00:47:45,361 because it was the first period in Earth history 852 00:47:45,487 --> 00:47:48,739 when large plants occupied Earth's surface, 853 00:47:48,866 --> 00:47:53,619 40, 50, 70 feet high, that grew in dense groves 854 00:47:53,745 --> 00:47:56,414 and produced a vast forest canopy 855 00:47:56,540 --> 00:47:59,083 and a steamy tropical jungle atmosphere 856 00:47:59,209 --> 00:48:03,754 that was something entirely new on the face of the Earth. 857 00:48:03,881 --> 00:48:06,215 narrator: This dense tropical swampland 858 00:48:06,341 --> 00:48:10,553 would dominate the Earth for the next 60 million years. 859 00:48:14,182 --> 00:48:15,600 The evidence is present 860 00:48:15,726 --> 00:48:20,021 on all of today's continents in the form of coal. 861 00:48:22,608 --> 00:48:24,984 The coal we use for fuel was formed 862 00:48:25,110 --> 00:48:28,905 from millions of years' worth of accumulated plant matter, 863 00:48:29,031 --> 00:48:33,409 most of which existed less than 300 million years ago. 864 00:48:38,874 --> 00:48:41,125 And it formed because of the unique way 865 00:48:41,251 --> 00:48:44,503 freshwater swamps decompose. 866 00:48:47,549 --> 00:48:50,134 - Okefenokee is derived from a Native American word 867 00:48:50,260 --> 00:48:52,803 that means "land of the trembling earth." 868 00:48:52,930 --> 00:48:55,514 lt's not very easy to walk through the swamp, 869 00:48:55,641 --> 00:49:00,186 because the subsurface is soggy plant remains. 870 00:49:00,312 --> 00:49:01,520 narrator: The freshwater 871 00:49:01,647 --> 00:49:03,731 prevents the vegetation from decaying, 872 00:49:03,857 --> 00:49:08,152 allowing huge amounts to build up over time. 873 00:49:08,278 --> 00:49:10,863 - Beneath me is not the regular sort of soil 874 00:49:10,989 --> 00:49:12,782 that you would have in your backyard. 875 00:49:12,908 --> 00:49:16,118 The soil that you see here is the plant material 876 00:49:16,244 --> 00:49:21,832 that accumulated last year or perhaps five years ago. 877 00:49:21,959 --> 00:49:23,918 lt's leaves, stems, twigs. 878 00:49:24,044 --> 00:49:26,170 There's still a good bit of water in this. 879 00:49:26,296 --> 00:49:29,632 But if we put this under a tremendous amount of pressure 880 00:49:29,758 --> 00:49:30,716 and add some heat, 881 00:49:30,842 --> 00:49:33,344 by covering over with layers of rock 882 00:49:33,470 --> 00:49:35,888 and leaving it in the ground for millions of years, 883 00:49:36,014 --> 00:49:38,057 eventually it will change to this. 884 00:49:38,183 --> 00:49:39,642 This is a piece of bituminous coal, 885 00:49:39,768 --> 00:49:44,105 and it's around the order of 200 million years old. 886 00:49:44,231 --> 00:49:45,356 narrator: As the dead plants 887 00:49:45,482 --> 00:49:47,817 were transformed to coal on land, 888 00:49:47,943 --> 00:49:50,653 the shallow waters surrounding the continents 889 00:49:50,779 --> 00:49:52,697 were preserving millions of generations 890 00:49:52,823 --> 00:49:55,074 of dead marine organisms 891 00:49:55,200 --> 00:50:00,496 that would become our other major fossil fuels, 892 00:50:00,622 --> 00:50:03,207 oil and gas. 893 00:50:03,333 --> 00:50:08,546 Every year, mankind mines almost 5,000 megatons of coal, 894 00:50:08,672 --> 00:50:11,382 30 billion barrels of oil, 895 00:50:11,508 --> 00:50:14,969 and 3,000 billion cubic meters of gas. 896 00:50:15,095 --> 00:50:17,555 This fertile period of Earth history 897 00:50:17,681 --> 00:50:21,934 has given us much of the energy we use today. 898 00:50:22,060 --> 00:50:24,687 Without it, the lndustrial Revolution 899 00:50:24,813 --> 00:50:26,939 may never have happened. 900 00:50:29,693 --> 00:50:32,737 Plants were not alone in making a new life on the land 901 00:50:32,863 --> 00:50:35,906 300 million years ago. 902 00:50:36,033 --> 00:50:39,869 As time went on, first enormous insects... 903 00:50:46,251 --> 00:50:49,378 Then ambitious amphibians 904 00:50:49,504 --> 00:50:53,049 and finally early reptilians left the seas 905 00:50:53,175 --> 00:50:56,802 to take their first steps on the muddy shorelines. 906 00:50:56,928 --> 00:51:01,390 The U.S. east coast back then would have teemed with monsters: 907 00:51:01,516 --> 00:51:03,768 three-foot millipedes on land, 908 00:51:03,894 --> 00:51:05,770 two-foot dragonflies in the air, 909 00:51:05,896 --> 00:51:10,566 and proto-alligators patrolling the nearby waters. 910 00:51:12,819 --> 00:51:16,322 The world was over 4 1/4 billion years old, 911 00:51:16,448 --> 00:51:18,115 and for the first time, 912 00:51:18,241 --> 00:51:23,746 the surface was host to a complete modern biosphere. 913 00:51:33,632 --> 00:51:35,966 But the all-conquering life-forms 914 00:51:36,093 --> 00:51:40,471 were about to experience a hell on Earth. 915 00:51:40,597 --> 00:51:42,306 Forces deep within 916 00:51:42,432 --> 00:51:44,266 were about to give life on the surface 917 00:51:44,392 --> 00:51:46,811 its sternest test ever. 918 00:51:46,937 --> 00:51:49,313 Enormous volcanic eruptions 919 00:51:49,439 --> 00:51:51,857 would herald the biggest mass extinction 920 00:51:51,983 --> 00:51:54,985 in the planet's entire history. 921 00:52:02,494 --> 00:52:06,247 250 million years ago: 922 00:52:06,373 --> 00:52:08,415 for hundreds of millions of years, 923 00:52:08,542 --> 00:52:09,667 life on the surface 924 00:52:09,793 --> 00:52:13,420 had faced numerous challenges to its survival 925 00:52:13,547 --> 00:52:17,258 but nothing on the scale of what was about to happen. 926 00:52:21,263 --> 00:52:23,848 ln what would one day become Siberia, 927 00:52:23,974 --> 00:52:27,893 the Earth's crust became a volcanic morass. 928 00:52:28,019 --> 00:52:32,189 The cause was a rare mantle plume eruption. 929 00:52:32,315 --> 00:52:34,441 No one knows for sure why they occur, 930 00:52:34,568 --> 00:52:37,695 but occasionally, huge masses of hot mantle 931 00:52:37,821 --> 00:52:41,574 from deep within the Earth surge upwards, 932 00:52:41,700 --> 00:52:45,327 melting and smashing the crust above. 933 00:52:45,453 --> 00:52:49,373 The eruptions continued for over 1 million years. 934 00:52:49,499 --> 00:52:55,921 They spewed out over 1 million cubic miles of molten rock, 935 00:52:56,047 --> 00:53:02,094 enough to bury the modern U.S.A. in a layer over 1 ,000 feet deep. 936 00:53:02,220 --> 00:53:04,722 Clouds of poisonous gases spread out 937 00:53:04,848 --> 00:53:07,016 and shrouded the entire globe. 938 00:53:12,022 --> 00:53:14,940 lt was too much for most species of life. 939 00:53:15,066 --> 00:53:19,069 Over 95% were driven to extinction. 940 00:53:23,325 --> 00:53:25,534 lt was the most cataclysmic event 941 00:53:25,660 --> 00:53:28,662 the planet has ever witnessed. 942 00:53:31,833 --> 00:53:37,796 The planet that emerged from the chaos was much changed. 943 00:53:37,923 --> 00:53:40,758 A new supercontinent, the great Pangaea, 944 00:53:40,884 --> 00:53:43,344 now dominated. 945 00:53:45,263 --> 00:53:48,265 And the climate was altering dramatically. 946 00:53:48,391 --> 00:53:50,559 Over the next 200 million years, 947 00:53:50,685 --> 00:53:54,605 oxygen and carbon dioxide would rise to new peaks. 948 00:53:54,731 --> 00:53:56,106 And under these conditions, 949 00:53:56,233 --> 00:53:58,776 the animals that had survived the extinction 950 00:53:58,902 --> 00:54:01,987 were to evolve into the most infamous creatures 951 00:54:02,113 --> 00:54:04,949 ever to walk the Earth... 952 00:54:05,075 --> 00:54:06,492 [screeching roar] 953 00:54:06,618 --> 00:54:08,535 The dinosaurs. 954 00:54:12,749 --> 00:54:14,667 Utah, U.S.A. 955 00:54:17,921 --> 00:54:21,757 Paleontologist Reese Barrick is on the hunt for dinosaurs. 956 00:54:24,010 --> 00:54:26,887 ln this dusty corner of the western U.S.A., 957 00:54:27,013 --> 00:54:30,140 the rocks are packed with their bones. 958 00:54:30,267 --> 00:54:32,810 - Almost 1/3 of the history of life on this planet 959 00:54:32,936 --> 00:54:34,853 was dominated by dinosaurs. 960 00:54:34,980 --> 00:54:38,107 lt really, truly is a dinosaur planet. 961 00:54:38,233 --> 00:54:41,235 We have, from the bottom of this slope, 962 00:54:41,361 --> 00:54:43,988 sediments that are 1 50 million years. 963 00:54:44,114 --> 00:54:46,073 And as you go up the slope, you actually end up 964 00:54:46,199 --> 00:54:49,952 in the Cretaceous at 125 million years. 965 00:54:57,002 --> 00:54:58,168 How we doin', Barb? 966 00:54:58,295 --> 00:55:00,004 - Doin' great. - Find anything fun? 967 00:55:00,130 --> 00:55:03,173 - A small rib and some interesting fragments. 968 00:55:03,300 --> 00:55:05,175 - Well, that's a start for the day. 969 00:55:05,302 --> 00:55:07,011 narrator: Compared to modern creatures, 970 00:55:07,137 --> 00:55:09,013 dinosaurs were enormous. 971 00:55:09,139 --> 00:55:12,433 The average mammal today is smaller than a dog. 972 00:55:12,559 --> 00:55:15,853 The average dinosaur was larger than a grizzly bear. 973 00:55:15,979 --> 00:55:18,981 [dinosaur roaring] 974 00:55:22,319 --> 00:55:24,903 - Marvin, excellent. Look at that. 975 00:55:25,030 --> 00:55:28,532 That is a spectacular therizinosaur claw. 976 00:55:28,658 --> 00:55:31,660 This animal's gonna have to be 300 kilograms, 977 00:55:31,786 --> 00:55:33,412 so it's about the size 978 00:55:33,538 --> 00:55:35,789 of a National Football League lineman. 979 00:55:35,915 --> 00:55:37,166 [chuckles] 980 00:55:37,292 --> 00:55:39,084 These are absolutely fantastic 981 00:55:39,210 --> 00:55:42,171 because they're very well-preserved bone. 982 00:55:42,297 --> 00:55:44,423 A perfect claw. 983 00:55:44,549 --> 00:55:47,926 Absolutely brilliant, Marvin. Nice job. 984 00:55:50,722 --> 00:55:53,098 narrator: The first recorded dinosaur fossil find 985 00:55:53,224 --> 00:55:56,226 was a bone discovered by young Mary Ann Mantell 986 00:55:56,353 --> 00:55:59,271 in England in 1 822. 987 00:55:59,397 --> 00:56:02,441 Her husband, Dr. Gideon Mantell, was intrigued 988 00:56:02,567 --> 00:56:04,026 and set about determining 989 00:56:04,152 --> 00:56:06,862 what type of creature it belonged to. 990 00:56:10,075 --> 00:56:13,994 The fossil was unlike anything he'd ever seen. 991 00:56:17,207 --> 00:56:18,957 After much research, 992 00:56:19,084 --> 00:56:21,585 he decided it was in fact a tooth 993 00:56:21,711 --> 00:56:25,381 from an enormous lizard. 994 00:56:25,507 --> 00:56:27,966 He named the beast lguanodon, 995 00:56:28,093 --> 00:56:31,804 after the iguana lizard he thought it resembled. 996 00:56:31,930 --> 00:56:35,599 Over the next few decades, across Europe and the U.S.A., 997 00:56:35,725 --> 00:56:38,519 more and more huge bones were unearthed, 998 00:56:38,645 --> 00:56:41,188 and given their similarity to modern lizards, 999 00:56:41,314 --> 00:56:44,608 the name dinosaur, meaning "terrible lizard," 1000 00:56:44,734 --> 00:56:45,943 was coined. 1001 00:56:46,069 --> 00:56:49,238 [dinosaur roaring] 1002 00:56:53,785 --> 00:56:55,661 But many paleontologists today 1003 00:56:55,787 --> 00:56:58,956 believe one of the reasons dinosaurs grew so large 1004 00:56:59,082 --> 00:57:00,791 was that they weren't cold-blooded 1005 00:57:00,917 --> 00:57:03,794 like today's lizards. 1006 00:57:03,920 --> 00:57:06,964 They were lukewarm-blooded. 1007 00:57:07,090 --> 00:57:08,465 This gave them the advantages 1008 00:57:08,591 --> 00:57:12,761 of both cold-blooded lizards and warm-blooded mammals. 1009 00:57:12,887 --> 00:57:15,556 - Dinosaurs were able to be active 1010 00:57:15,682 --> 00:57:17,641 and collect food all year long, 1011 00:57:17,767 --> 00:57:19,476 and yet they could put a greater amount 1012 00:57:19,602 --> 00:57:21,228 of the food that they ate towards growing 1013 00:57:21,354 --> 00:57:23,981 as opposed to just heat generation. 1014 00:57:24,107 --> 00:57:25,858 narrator: But another reason for their size 1015 00:57:25,984 --> 00:57:28,735 may have been the sweltering oxygen-rich environment 1016 00:57:28,862 --> 00:57:31,905 that came to dominate the dinosaur era, 1017 00:57:32,031 --> 00:57:35,284 an environment triggered by volcanism. 1018 00:57:43,293 --> 00:57:46,670 Starting around 1 80 million years ago, 1019 00:57:46,796 --> 00:57:49,840 a new upsurge in volcanic activity 1020 00:57:49,966 --> 00:57:53,177 split apart the supercontinent. 1021 00:57:53,303 --> 00:57:56,221 The continental fragments began their long journeys 1022 00:57:56,347 --> 00:57:59,683 into the positions they occupy today. 1023 00:57:59,809 --> 00:58:04,229 North America, South America, Africa, and Europe 1024 00:58:04,355 --> 00:58:07,357 all went their separate ways. 1025 00:58:07,484 --> 00:58:12,696 The Pangaean supercontinent was no more. 1026 00:58:12,822 --> 00:58:15,782 Each of the new continents still carried dinosaurs, 1027 00:58:15,909 --> 00:58:20,329 and the steamy volcanic climate seemed to suit them. 1028 00:58:21,581 --> 00:58:24,958 lt was global warming gone wild. 1029 00:58:25,084 --> 00:58:32,216 CO2 levels increased over 500%, and temperatures soared. 1030 00:58:32,342 --> 00:58:34,635 ln the greenhouse conditions this created, 1031 00:58:34,761 --> 00:58:40,390 huge tropical forests spread across many of the continents. 1032 00:58:40,517 --> 00:58:42,434 - The increasing amount of tropics 1033 00:58:42,560 --> 00:58:44,311 meant that there was a lot more lush vegetation, 1034 00:58:44,437 --> 00:58:46,730 which means there's a lot more food for dinosaurs, 1035 00:58:46,856 --> 00:58:49,107 which allowed them not only to specialize 1036 00:58:49,234 --> 00:58:50,359 and evolve to specialize 1037 00:58:50,485 --> 00:58:52,236 on different types of plant materials 1038 00:58:52,362 --> 00:58:55,614 but allowed them to get extremely large. 1039 00:58:58,451 --> 00:58:59,743 narrator: Many scientists believe 1040 00:58:59,869 --> 00:59:01,620 that evolving for millions of years 1041 00:59:01,746 --> 00:59:04,206 in this warm oxygen-rich world 1042 00:59:04,332 --> 00:59:06,500 allowed the lukewarm-blooded dinosaurs 1043 00:59:06,626 --> 00:59:09,253 to reach their enormous sizes. 1044 00:59:09,379 --> 00:59:12,923 Huge dinosaurs may have been a biological response 1045 00:59:13,049 --> 00:59:16,218 to a volcanically overactive planet. 1046 00:59:17,804 --> 00:59:20,305 But size would not save the dinosaurs 1047 00:59:20,431 --> 00:59:23,433 from what was to come. 1048 00:59:23,560 --> 00:59:25,185 Their time on Earth would end 1049 00:59:25,311 --> 00:59:28,188 in sudden, unstoppable devastation. 1050 00:59:43,413 --> 00:59:48,834 1 00 million years ago, 1051 00:59:48,960 --> 00:59:52,546 planet Earth was ruled by dinosaurs. 1052 00:59:52,672 --> 00:59:55,674 [dinosaur screeching] 1053 00:59:57,927 --> 01:00:02,264 Huge beasts filled the land, the sea, and the air. 1054 01:00:05,059 --> 01:00:11,732 They lived in a sweltering world defined by overactive volcanism, 1055 01:00:11,858 --> 01:00:13,358 and before it was finished, 1056 01:00:13,484 --> 01:00:16,153 this volcanism would bring to the surface 1057 01:00:16,279 --> 01:00:20,198 some of the planet's most wondrous riches: 1058 01:00:20,325 --> 01:00:21,950 diamonds. 1059 01:00:28,082 --> 01:00:30,208 Kimberley, South Africa: 1060 01:00:30,335 --> 01:00:33,712 Jock Robey is chief geologist at De Beers, 1061 01:00:33,838 --> 01:00:36,757 the largest diamond company in the world. 1062 01:00:36,883 --> 01:00:39,509 - Diamond is simply the high-pressure form 1063 01:00:39,636 --> 01:00:42,137 of the element carbon. 1064 01:00:42,263 --> 01:00:46,475 This is a typical eight-sided crystal called an octahedron. 1065 01:00:46,601 --> 01:00:50,145 Uncut, it is worth $2,000 a carat. 1066 01:00:50,271 --> 01:00:53,857 As a cut stone, it would probably sell for $80,000. 1067 01:00:53,983 --> 01:00:55,359 narrator: For thousands of years, 1068 01:00:55,485 --> 01:00:57,277 diamonds had been found worldwide 1069 01:00:57,403 --> 01:00:59,529 washed up in sandy riverbanks, 1070 01:00:59,656 --> 01:01:04,034 but their source had remained a total mystery. 1071 01:01:04,160 --> 01:01:06,328 lt was not until 1 869 1072 01:01:06,454 --> 01:01:08,622 when huge unique diamond discoveries 1073 01:01:08,748 --> 01:01:10,248 were made in South Africa 1074 01:01:10,375 --> 01:01:13,377 that their remarkable origin was revealed. 1075 01:01:13,503 --> 01:01:15,379 - What is special about the diamonds 1076 01:01:15,505 --> 01:01:17,172 found in the Kimberley area 1077 01:01:17,298 --> 01:01:19,257 was, here, for the first time ever, 1078 01:01:19,384 --> 01:01:23,387 they found the source rock of diamonds. 1079 01:01:23,513 --> 01:01:26,473 This is a piece of rock mined from the kimberlite, 1080 01:01:26,599 --> 01:01:30,560 and as we turn it, it contains a diamond. 1081 01:01:30,687 --> 01:01:32,854 narrator: The diamond-bearing rock was extracted 1082 01:01:32,980 --> 01:01:35,732 from strange vertical formations. 1083 01:01:35,858 --> 01:01:39,319 - As the miners were digging, they found that the diamonds 1084 01:01:39,445 --> 01:01:42,072 were contained in a body of rock 1085 01:01:42,198 --> 01:01:44,700 that had a shape of an ice cream cone: 1086 01:01:44,826 --> 01:01:48,078 slightly broader at the surface, yellow in color, 1087 01:01:48,204 --> 01:01:51,623 tapering down to a narrower point. 1088 01:01:57,547 --> 01:01:58,964 narrator: Henry Carvill Lewis, 1089 01:01:59,090 --> 01:02:01,466 a visiting American mineralogist, 1090 01:02:01,592 --> 01:02:03,927 put together the pieces. 1091 01:02:04,053 --> 01:02:05,762 He realized these diamond mines 1092 01:02:05,888 --> 01:02:10,642 were actually the mouths of ancient volcanoes. 1093 01:02:10,768 --> 01:02:13,437 The miners were digging down into their roots, 1094 01:02:13,563 --> 01:02:17,232 through the diamond-bearing magma that remained. 1095 01:02:19,944 --> 01:02:22,988 But these were clearly not normal volcanoes. 1096 01:02:23,114 --> 01:02:25,782 They were over three times deeper, 1097 01:02:25,908 --> 01:02:27,784 extending nearly 1 00 miles 1098 01:02:27,910 --> 01:02:30,787 beneath the surface of the continent. 1099 01:02:30,913 --> 01:02:34,291 Uniquely intense pressures and temperatures at this depth 1100 01:02:34,417 --> 01:02:37,502 make it the only place that diamonds can form, 1101 01:02:37,628 --> 01:02:39,588 and the diamonds could only be brought up 1102 01:02:39,714 --> 01:02:42,215 by uniquely intense eruptions. 1103 01:02:42,341 --> 01:02:45,051 The diamond-bearing magma exploded out of the Earth 1104 01:02:45,178 --> 01:02:48,305 at over 300 miles an hour. 1105 01:02:48,431 --> 01:02:51,016 - lmagine the force and the power of this volcano 1106 01:02:51,142 --> 01:02:53,310 to cut those sheer vertical walls 1107 01:02:53,436 --> 01:02:55,812 and blow this up another thousand meters. 1108 01:02:55,938 --> 01:02:58,398 This is the power of these volcanoes. 1109 01:03:06,407 --> 01:03:08,658 narrator: When the Pangaean supercontinent split apart 1110 01:03:08,785 --> 01:03:10,494 over 1 00 million years ago, 1111 01:03:10,620 --> 01:03:12,829 scientists believe the enormous upheaval 1112 01:03:12,955 --> 01:03:15,707 triggered these supereruptions. 1113 01:03:15,833 --> 01:03:18,418 Because supercontinental breakups are rare, 1114 01:03:18,544 --> 01:03:21,671 so are the diamonds they bring to the surface. 1115 01:03:21,798 --> 01:03:24,966 The diamonds that erupted into the dinosaur world 1116 01:03:25,092 --> 01:03:29,513 would survive unblemished until the present day. 1117 01:03:29,639 --> 01:03:33,475 But the dinosaurs would not be so lucky. 1118 01:03:40,650 --> 01:03:44,986 65 million years ago, 1119 01:03:45,112 --> 01:03:47,072 the planet was lush. 1120 01:03:47,198 --> 01:03:50,992 Vegetation was thick on the surface. 1121 01:03:51,118 --> 01:03:54,871 Living things were prospering like never before. 1122 01:03:54,997 --> 01:03:56,540 But the dominant dinosaurs 1123 01:03:56,666 --> 01:03:59,709 were about to be wiped from the face of the planet. 1124 01:03:59,836 --> 01:04:01,628 [dinosaur roaring] 1125 01:04:01,754 --> 01:04:04,381 - Dinosaur bones are found continuously 1126 01:04:04,507 --> 01:04:06,508 throughout the sedimentary record 1127 01:04:06,634 --> 01:04:09,261 from 230 million years ago 1128 01:04:09,387 --> 01:04:11,388 right up to 65 million years ago, 1129 01:04:11,514 --> 01:04:14,850 and then, instantaneously, they vanish. 1130 01:04:16,769 --> 01:04:18,144 narrator: Not only dinosaurs 1131 01:04:18,271 --> 01:04:23,066 but over 70% of species on Earth disappeared. 1132 01:04:23,192 --> 01:04:26,361 From plant life upward, something terrible had happened 1133 01:04:26,487 --> 01:04:29,739 to the entire ecosystem of the planet. 1134 01:04:33,744 --> 01:04:36,079 This mass extinction remained a mystery 1135 01:04:36,205 --> 01:04:39,457 for generations of paleontologists. 1136 01:04:39,584 --> 01:04:42,127 But it is a mystery no longer. 1137 01:04:44,630 --> 01:04:46,756 Colorado, U.S.A.: 1138 01:04:46,883 --> 01:04:49,009 Dan Durda is taking samples 1139 01:04:49,135 --> 01:04:55,098 from an exposed layer of rock exactly 65 million years old. 1140 01:04:55,224 --> 01:04:58,268 Scientists now believe that it holds the answer. 1141 01:04:58,394 --> 01:05:01,229 For Dan Durda, this powdery rock 1142 01:05:01,355 --> 01:05:03,940 is an indication that the dinosaurs perished 1143 01:05:04,066 --> 01:05:06,943 in a sudden astronomical catastrophe. 1144 01:05:07,069 --> 01:05:10,822 - Dinosaurs and 75% of all the other plants and animals 1145 01:05:10,948 --> 01:05:13,783 that lived with them, this layer is their tombstone. 1146 01:05:13,910 --> 01:05:17,370 This thin layer of clay is the important evidence 1147 01:05:17,496 --> 01:05:20,624 of a violent event in the history 1148 01:05:20,750 --> 01:05:22,083 of life on the planet. 1149 01:05:22,209 --> 01:05:24,419 narrator: The evidence held in the tombstone layer 1150 01:05:24,545 --> 01:05:25,712 is a huge amount 1151 01:05:25,838 --> 01:05:30,133 of an exceptionally rare element, iridium. 1152 01:05:30,259 --> 01:05:32,302 The remarkable concentration of iridium 1153 01:05:32,428 --> 01:05:34,930 was discovered accidentally in 1 980 1154 01:05:35,056 --> 01:05:37,515 by a father-and-son team of scientists, 1155 01:05:37,642 --> 01:05:41,394 Luis and Walter Alvarez. 1156 01:05:41,520 --> 01:05:43,146 On the planet's surface, 1157 01:05:43,272 --> 01:05:47,150 iridium is usually found in very small concentrations. 1158 01:05:47,276 --> 01:05:50,320 Most of this rare element originates from space rock 1159 01:05:50,446 --> 01:05:52,822 deposited from the multitude of small meteors 1160 01:05:52,949 --> 01:05:56,660 vaporizing in the upper atmosphere every day. 1161 01:05:56,786 --> 01:05:58,745 The Alvarezes were looking for variations 1162 01:05:58,871 --> 01:06:01,539 in the strength of these tiny meteor showers, 1163 01:06:01,666 --> 01:06:03,959 but when they realized this huge concentration 1164 01:06:04,085 --> 01:06:06,503 was held in the infamous tombstone layer, 1165 01:06:06,629 --> 01:06:09,881 they proposed a radical new theory for the extinction: 1166 01:06:10,007 --> 01:06:12,300 death from above. 1167 01:06:12,426 --> 01:06:18,181 The dinosaur planet had been hit by an enormous meteor. 1168 01:06:18,307 --> 01:06:21,518 Their theory remained controversial for over ten years 1169 01:06:21,644 --> 01:06:23,353 until the final piece of the puzzle 1170 01:06:23,479 --> 01:06:27,023 was discovered in Mexico: 1171 01:06:27,149 --> 01:06:31,528 a hidden crater over 1 00 miles across. 1172 01:06:31,654 --> 01:06:34,531 - ln 1 990, the Chicxulub impact crater was discovered, 1173 01:06:34,657 --> 01:06:36,533 and its age, when finally dated, 1174 01:06:36,659 --> 01:06:39,285 turned out to be precisely 65 million years old. 1175 01:06:39,412 --> 01:06:40,453 lt turned out to be, 1176 01:06:40,579 --> 01:06:43,081 it was the smoking gun for the Alvarez theory. 1177 01:06:43,207 --> 01:06:45,709 narrator: Worldwide, the tombstone layer 1178 01:06:45,835 --> 01:06:50,213 contains an estimated 200,000 tons of iridium. 1179 01:06:50,339 --> 01:06:56,052 This translates to a meteor over six miles in diameter. 1180 01:06:56,178 --> 01:07:00,223 lts impact on the planet would have been devastating. 1181 01:07:00,349 --> 01:07:01,850 - You've got to imagine Mount Everest 1182 01:07:01,976 --> 01:07:05,979 flying at you across the sky at 20 kilometers per second. 1183 01:07:18,534 --> 01:07:20,410 Several thousand cubic kilometers 1184 01:07:24,582 --> 01:07:26,833 and launched around the entire planet, 1185 01:07:26,959 --> 01:07:29,419 slowly raining back down through the atmosphere 1186 01:07:29,545 --> 01:07:31,212 to settle across the surface of the Earth 1187 01:07:31,338 --> 01:07:34,257 as a thin layer of dust and debris. 1188 01:07:37,053 --> 01:07:38,762 narrator: But the meteor was not alone 1189 01:07:38,888 --> 01:07:41,264 in wreaking destruction. 1190 01:07:41,390 --> 01:07:44,309 Today in lndia, ancient lava flows exist 1191 01:07:44,435 --> 01:07:45,685 that are so thick, 1192 01:07:45,811 --> 01:07:49,314 whole temples have been carved into their layers. 1193 01:07:49,440 --> 01:07:51,983 The lavas were the result of a massive eruption 1194 01:07:52,109 --> 01:07:54,027 that was occurring simultaneously 1195 01:07:54,153 --> 01:07:55,737 with the meteor strike. 1196 01:07:55,863 --> 01:07:57,238 Although not as extensive 1197 01:07:57,364 --> 01:07:59,574 as the earlier Siberian eruptions, 1198 01:07:59,700 --> 01:08:01,868 these lava flows in western lndia 1199 01:08:01,994 --> 01:08:06,122 could have buried the U.S.A. to a depth of over 600 feet. 1200 01:08:06,248 --> 01:08:09,209 The huge clouds of toxic dust they produced 1201 01:08:09,335 --> 01:08:12,295 would have rivaled those of the meteor. 1202 01:08:12,421 --> 01:08:14,214 65 million years ago, 1203 01:08:14,340 --> 01:08:16,424 the meteor impact and the eruptions 1204 01:08:16,550 --> 01:08:19,803 would have been a deadly double blow. 1205 01:08:19,929 --> 01:08:21,930 Whichever had the stronger effect, 1206 01:08:22,056 --> 01:08:23,890 the combination of these events 1207 01:08:24,016 --> 01:08:26,935 sounded the death knell for the dinosaurs. 1208 01:08:27,061 --> 01:08:30,063 [dinosaur roaring] 1209 01:08:31,816 --> 01:08:34,651 A dust cloud lingering high in the upper atmosphere 1210 01:08:34,777 --> 01:08:39,155 and blocking the sun devastated the life below. 1211 01:08:39,281 --> 01:08:41,157 The huge dinosaurs, 1212 01:08:41,283 --> 01:08:43,743 along with most other major species, 1213 01:08:43,869 --> 01:08:45,203 were extinct. 1214 01:08:45,329 --> 01:08:47,122 The new world that was to follow 1215 01:08:47,248 --> 01:08:50,792 would be the world of the mammals 1216 01:08:50,918 --> 01:08:53,128 and the world of man. 1217 01:08:59,802 --> 01:09:03,096 50 million years ago, 1218 01:09:03,222 --> 01:09:06,724 life was slowly recovering after the cataclysmic extinction 1219 01:09:06,851 --> 01:09:10,019 that obliterated the dinosaurs. 1220 01:09:10,146 --> 01:09:15,483 The Earth had been around for over 4.4 billion years, 1221 01:09:15,609 --> 01:09:17,986 but only now were the first mammals, 1222 01:09:18,112 --> 01:09:22,031 our ancestors, beginning to flourish. 1223 01:09:22,158 --> 01:09:24,367 Long before humans arrived, 1224 01:09:24,493 --> 01:09:28,663 the continents continued to move and crash into one another. 1225 01:09:28,789 --> 01:09:32,167 Slowly but surely, the surface started to look familiar 1226 01:09:32,293 --> 01:09:34,377 as plate tectonics and erosion 1227 01:09:34,503 --> 01:09:38,006 created the dramatic landscapes we see today. 1228 01:09:45,014 --> 01:09:49,893 The Swiss Alps: 1229 01:09:50,019 --> 01:09:52,687 some mountain chains can be explained 1230 01:09:52,813 --> 01:09:57,567 by volcanic eruption of rock from the depths of the Earth. 1231 01:09:57,693 --> 01:10:00,445 But the greatest, including the Alps, 1232 01:10:00,571 --> 01:10:02,572 contain no volcanoes. 1233 01:10:02,698 --> 01:10:05,575 They appear to have risen as if by magic 1234 01:10:05,701 --> 01:10:08,328 up from the plains beneath. 1235 01:10:10,998 --> 01:10:13,958 This famous range runs through the heart of Europe 1236 01:10:14,084 --> 01:10:18,963 and reaches over three miles above sea level. 1237 01:10:19,089 --> 01:10:25,386 How was such a huge mass of rock pushed up so high? 1238 01:10:32,311 --> 01:10:34,270 Adrian Pfiffner is an expert 1239 01:10:34,396 --> 01:10:37,732 on the structure of the Alpine chain, 1240 01:10:37,858 --> 01:10:39,943 and he knows the answer. 1241 01:10:40,069 --> 01:10:41,986 - The scene we see in front of us 1242 01:10:42,112 --> 01:10:45,573 is the result of a collision between two continents, 1243 01:10:45,699 --> 01:10:49,744 the African continent and the European continent. 1244 01:10:53,582 --> 01:10:55,500 narrator: A close study of the Alpine rocks 1245 01:10:55,626 --> 01:10:57,502 can provide clear evidence 1246 01:10:57,628 --> 01:11:00,171 of how the mountains were formed. 1247 01:11:00,297 --> 01:11:03,091 The secret is revealed in quartz crystals 1248 01:11:03,217 --> 01:11:05,260 that are extremely small. 1249 01:11:05,386 --> 01:11:10,306 - These slices are about 25 thousandths of a millimeter. 1250 01:11:10,432 --> 01:11:11,641 At that thickness, 1251 01:11:11,767 --> 01:11:14,811 you see through one single grain. 1252 01:11:14,937 --> 01:11:16,521 narrator: The tiny crystals in the rock 1253 01:11:16,647 --> 01:11:18,690 reveal massive deformation. 1254 01:11:18,816 --> 01:11:23,111 - The quartz grains have been really stretched, 1255 01:11:23,237 --> 01:11:25,029 elongated and flattened. 1256 01:11:25,155 --> 01:11:29,200 You need large stresses in order to deform these rocks. 1257 01:11:29,326 --> 01:11:31,160 One process that is doing this 1258 01:11:31,287 --> 01:11:35,456 is actually the collision of two continental plates. 1259 01:11:35,582 --> 01:11:37,875 narrator: For the last 45 million years, 1260 01:11:38,002 --> 01:11:40,461 as the continents have continued to move, 1261 01:11:40,587 --> 01:11:46,342 the African plate and subplates have been grinding into Europe. 1262 01:11:46,468 --> 01:11:48,761 The continental crust along the collision point 1263 01:11:48,887 --> 01:11:51,306 experiences extreme pressure, 1264 01:11:51,432 --> 01:11:55,518 and the solid rock itself is warped and buckled. 1265 01:11:55,644 --> 01:11:58,271 - lf you assume that my hands are two plates 1266 01:11:58,397 --> 01:12:00,356 which are squeezing the rocks in between, 1267 01:12:00,482 --> 01:12:03,484 you can see that some of the material escapes upwards 1268 01:12:03,610 --> 01:12:06,237 and leads to the building of a mountain chain. 1269 01:12:06,363 --> 01:12:09,866 narrator: The twisted folds of the rock strata are exposed 1270 01:12:09,992 --> 01:12:17,540 as the mountains are slowly squeezed higher and higher. 1271 01:12:17,666 --> 01:12:20,418 One famous Alpine mountain 1272 01:12:20,544 --> 01:12:22,462 demonstrates clearly this collision 1273 01:12:22,588 --> 01:12:27,759 of the African and European continental plates: 1274 01:12:27,885 --> 01:12:30,720 the Matterhorn. 1275 01:12:30,846 --> 01:12:35,683 The Matterhorn is the child of two continents. 1276 01:12:38,062 --> 01:12:40,104 - What's amazing about the Matterhorn is, 1277 01:12:40,230 --> 01:12:42,357 the top pyramid of the Matterhorn 1278 01:12:42,483 --> 01:12:45,902 is a piece of Africa, and it lies on Europe. 1279 01:12:46,028 --> 01:12:48,404 narrator: ln the formation of this classic mountain, 1280 01:12:48,530 --> 01:12:52,533 the two continental plates have actually overlapped. 1281 01:12:52,659 --> 01:12:54,327 - You can think of a car crash. 1282 01:12:54,453 --> 01:12:56,621 lf two cars crash with each other, 1283 01:12:56,747 --> 01:12:59,082 maybe one car slides over the other one. 1284 01:12:59,208 --> 01:13:01,584 The two continents moved together, 1285 01:13:01,710 --> 01:13:04,962 and Africa moved on top of Europe. 1286 01:13:05,089 --> 01:13:07,340 narrator: Plate tectonics are responsible 1287 01:13:07,466 --> 01:13:10,426 for all the Earth's mountain ranges, 1288 01:13:10,552 --> 01:13:12,762 and over millions of years of growth, 1289 01:13:12,888 --> 01:13:14,722 the only thing that has stopped them 1290 01:13:14,848 --> 01:13:18,434 grinding inexorably skywards is erosion... 1291 01:13:21,230 --> 01:13:24,941 Erosion by snow, wind, and rain. 1292 01:13:25,067 --> 01:13:30,113 - This is the action of water that is eroding the mountains. 1293 01:13:30,239 --> 01:13:33,324 Now, this might seem to be something very small, 1294 01:13:33,450 --> 01:13:36,077 but actually, if you look at the entire Swiss Alps, 1295 01:13:36,203 --> 01:13:39,622 50 million tons is eroded every year, 1296 01:13:39,748 --> 01:13:42,125 and this corresponds to a small mountain 1297 01:13:42,251 --> 01:13:45,336 roughly 1 ,000 meters high, one every year. 1298 01:13:49,174 --> 01:13:51,134 narrator: The height of mountains around the world 1299 01:13:51,260 --> 01:13:54,679 are determined by these two opposing forces--- 1300 01:13:54,805 --> 01:13:57,640 uplift and erosion--- 1301 01:13:57,766 --> 01:13:59,809 changing them by fractions of an inch, 1302 01:13:59,935 --> 01:14:03,688 up or down, each year. 1303 01:14:03,814 --> 01:14:06,649 But plate movement and water erosion 1304 01:14:06,775 --> 01:14:09,861 can also create the opposite of a mountain. 1305 01:14:09,987 --> 01:14:11,237 Under the right conditions, 1306 01:14:11,363 --> 01:14:14,657 the surface itself can be cut away, 1307 01:14:14,783 --> 01:14:18,286 sometimes spectacularly. 1308 01:14:23,041 --> 01:14:25,751 The Grand Canyon: 1309 01:14:25,878 --> 01:14:29,505 over 1 mile deep, 1310 01:14:29,631 --> 01:14:35,052 1 0 miles wide, 1311 01:14:35,179 --> 01:14:39,432 277 miles long, 1312 01:14:39,558 --> 01:14:42,268 and still growing. 1313 01:14:42,394 --> 01:14:44,145 - One of the great stories of exploration 1314 01:14:44,271 --> 01:14:45,646 is when the first Europeans 1315 01:14:45,772 --> 01:14:48,399 saw the Grand Canyon in the year 1 541 , 1316 01:14:48,525 --> 01:14:50,693 and a couple of those men came over to the rim, 1317 01:14:50,819 --> 01:14:52,445 they saw the river down below, 1318 01:14:52,571 --> 01:14:55,406 and they thought it was six feet wide. 1319 01:14:55,532 --> 01:14:57,533 The explorer sent a couple of his men down, 1320 01:14:57,659 --> 01:14:59,202 and they came back later and said, 1321 01:14:59,328 --> 01:15:01,579 "The canyon is deeper than it looks." 1322 01:15:04,625 --> 01:15:06,209 narrator: Wayne Ranney is an expert 1323 01:15:06,335 --> 01:15:08,377 on this geological phenomenon, 1324 01:15:08,504 --> 01:15:13,341 its unique scale the consequence of titanic forces of nature. 1325 01:15:16,678 --> 01:15:19,514 Over the course of the last 6 million years, 1326 01:15:19,640 --> 01:15:22,266 this spectacular canyon has been carved 1327 01:15:22,392 --> 01:15:25,478 by the slow, winding Colorado River 1328 01:15:25,604 --> 01:15:28,606 in combination with dramatic uplifting 1329 01:15:28,732 --> 01:15:31,359 of the Colorado Plateau. 1330 01:15:34,404 --> 01:15:35,905 Plate tectonic processes 1331 01:15:36,031 --> 01:15:38,908 have pushed the whole plateau upwards. 1332 01:15:39,034 --> 01:15:43,746 lt now lies over 8,000 feet above sea level. 1333 01:15:43,872 --> 01:15:45,957 - This uplift probably occurred 1334 01:15:46,083 --> 01:15:49,085 with the Pacific plate coming into the North American plate 1335 01:15:49,211 --> 01:15:50,962 and wrinkling the crust, 1336 01:15:51,088 --> 01:15:53,881 much like if you took a throw rug on a hardwood floor 1337 01:15:54,007 --> 01:15:56,008 and pushed it along the hardwood floor. 1338 01:15:56,134 --> 01:15:58,094 When the edge of that rug reaches the wall, 1339 01:15:58,220 --> 01:16:00,012 you'll see this big bow-up in the rug, 1340 01:16:00,138 --> 01:16:01,597 and that's exactly what's happened 1341 01:16:01,723 --> 01:16:04,767 to the western edge of North America. 1342 01:16:04,893 --> 01:16:06,269 narrator: The river looks too small 1343 01:16:06,395 --> 01:16:08,938 to cut a canyon so deep, 1344 01:16:09,064 --> 01:16:11,732 but its height above sea level 1345 01:16:11,858 --> 01:16:16,070 means that the force of gravity gives it great power. 1346 01:16:19,283 --> 01:16:20,950 - All you have to do is look at big rivers 1347 01:16:21,076 --> 01:16:23,035 like the Amazon or the Mississippi. 1348 01:16:23,161 --> 01:16:25,037 They have much more volume of water 1349 01:16:25,163 --> 01:16:26,581 than the Colorado River does, 1350 01:16:26,707 --> 01:16:28,374 and yet they don't cut large canyons, 1351 01:16:28,500 --> 01:16:30,668 because their landscape is not elevated. 1352 01:16:30,794 --> 01:16:33,671 So uplift brings the rocks into an elevation 1353 01:16:33,797 --> 01:16:35,506 where the river can then saw down 1354 01:16:35,632 --> 01:16:36,799 through all of those layers 1355 01:16:36,925 --> 01:16:41,554 and create the canyon landscape we see today. 1356 01:16:41,680 --> 01:16:43,973 narrator: Plate tectonics combined with erosion 1357 01:16:44,099 --> 01:16:45,808 have sculpted many of the features 1358 01:16:45,934 --> 01:16:47,893 on the surface of our planet, 1359 01:16:48,020 --> 01:16:51,314 and as a general rule, the mostjagged, tallest peaks 1360 01:16:51,440 --> 01:16:52,815 and the deepest canyons 1361 01:16:52,941 --> 01:16:55,651 are the youngest of these grand structures, 1362 01:16:55,777 --> 01:17:00,823 all formed within the last 50 million years. 1363 01:17:00,949 --> 01:17:03,326 But the final touches have been added 1364 01:17:03,452 --> 01:17:08,331 by yet another major force of nature. 1365 01:17:08,457 --> 01:17:11,167 2 million years ago in east Africa, 1366 01:17:11,293 --> 01:17:12,877 ancestors of modern humans 1367 01:17:13,003 --> 01:17:18,674 were taking their first steps on Earth. 1368 01:17:18,800 --> 01:17:21,844 At the same time, down from the North Pole, 1369 01:17:21,970 --> 01:17:26,349 enormous icy glaciers began to descend. 1370 01:17:26,475 --> 01:17:30,603 The Earth was about to enter the ice ages. 1371 01:17:35,984 --> 01:17:40,529 2 million years ago, ancestors of modern humans 1372 01:17:40,656 --> 01:17:44,533 had begun to spread out of Africa. 1373 01:17:44,660 --> 01:17:48,746 But the Earth around them was cooling down. 1374 01:17:48,872 --> 01:17:50,539 Before long, much of the planet 1375 01:17:50,666 --> 01:17:54,043 would be coated in huge glaciers. 1376 01:17:54,169 --> 01:17:57,421 The ice ages had arrived. 1377 01:18:00,592 --> 01:18:02,677 The grand freezings were triggered 1378 01:18:02,803 --> 01:18:05,221 when overflowing volcanoes in Panama 1379 01:18:05,347 --> 01:18:09,058 created the land bridge joining North to South America 1380 01:18:09,184 --> 01:18:13,646 and radically altered global ocean currents. 1381 01:18:13,772 --> 01:18:18,693 The polar seas cooled significantly. 1382 01:18:18,819 --> 01:18:21,779 The result was that pronounced dips in global temperature 1383 01:18:21,905 --> 01:18:24,615 could now tip the planet into ice ages 1384 01:18:24,741 --> 01:18:28,077 lasting tens of thousands of years. 1385 01:18:34,710 --> 01:18:36,752 lceland: 1386 01:18:36,878 --> 01:18:39,213 the Langjökull glacier. 1387 01:18:41,091 --> 01:18:43,718 ln the highest, coldest parts of the planet, 1388 01:18:43,844 --> 01:18:47,972 glaciers still reign supreme. 1389 01:18:51,309 --> 01:18:54,937 Few venture out in these hostile terrains, 1390 01:18:55,063 --> 01:18:58,774 but glacier climatologist Finnur Pálsson and his team 1391 01:18:58,900 --> 01:19:01,736 regularly battle the freezing elements. 1392 01:19:03,530 --> 01:19:05,698 - When you're doing glacier fieldwork, 1393 01:19:05,824 --> 01:19:08,617 conditions can be very bad. 1394 01:19:08,744 --> 01:19:14,290 narrator: Outside, it is below minus 20 degrees Fahrenheit. 1395 01:19:14,416 --> 01:19:18,961 - l like to work in harsh conditions. 1396 01:19:19,087 --> 01:19:21,797 Difficulty is something you need to tackle. 1397 01:19:21,923 --> 01:19:25,634 narrator: Finnur is keeping tabs on the growth of the glacier. 1398 01:19:25,761 --> 01:19:29,805 At present, it is over 350 square miles, 1399 01:19:29,931 --> 01:19:32,433 the size of New York City. 1400 01:19:32,559 --> 01:19:34,268 And although it may look static, 1401 01:19:34,394 --> 01:19:37,688 in fact, it is in constant motion. 1402 01:19:37,814 --> 01:19:44,987 Glaciers are formed initially by snowfall on high areas. 1403 01:19:45,113 --> 01:19:47,490 The compacted ice is then dragged down 1404 01:19:47,616 --> 01:19:50,493 by the force of gravity. 1405 01:19:50,619 --> 01:19:54,497 The glaciers move like slow-motion rivers. 1406 01:19:54,623 --> 01:19:56,081 - You can think of ice 1407 01:19:56,208 --> 01:19:59,168 as soft material like toothpaste. 1408 01:19:59,294 --> 01:20:02,004 lt flows. 1409 01:20:02,130 --> 01:20:06,467 lf you make a big blob of toothpaste on a plate, 1410 01:20:06,593 --> 01:20:11,013 it will slowly sink down and flow away to the edges. 1411 01:20:11,139 --> 01:20:14,433 narrator: Finnur and his team in lceland regularly check 1412 01:20:14,559 --> 01:20:17,937 on the incremental movement of the ice. 1413 01:20:21,900 --> 01:20:24,735 - This is a satellite positioning system. 1414 01:20:24,861 --> 01:20:27,988 We can calculate the position of this point 1415 01:20:28,114 --> 01:20:30,366 with an accuracy of about two centimeters 1416 01:20:30,492 --> 01:20:33,536 to calculate how fast the glacier moves. 1417 01:20:33,662 --> 01:20:35,704 narrator: Finnur's measurements tell him 1418 01:20:35,831 --> 01:20:41,544 that this glacier is moving at over 1 50 feet per year. 1419 01:20:41,670 --> 01:20:43,045 ln today's mild temperatures, 1420 01:20:43,171 --> 01:20:46,423 glacial advance is kept in check by glacial melting, 1421 01:20:46,550 --> 01:20:48,384 but if global temperatures were to drop 1422 01:20:48,510 --> 01:20:50,886 byjust a few degrees for a long period, 1423 01:20:51,012 --> 01:20:53,347 then the glaciers would grind slowly forward, 1424 01:20:53,473 --> 01:20:57,017 and the Earth would enter another ice age. 1425 01:20:57,143 --> 01:21:00,020 The existence of ice ages was first discovered 1426 01:21:00,146 --> 01:21:04,525 by 1 9th-century Swiss geologist Louis Agassiz. 1427 01:21:04,651 --> 01:21:07,444 As he explored the Swiss Alps in the 1 830s, 1428 01:21:07,571 --> 01:21:09,321 Agassiz couldn't help but notice 1429 01:21:09,447 --> 01:21:13,576 the immense boulders scattered over farmland 1430 01:21:13,702 --> 01:21:17,580 and the bizarre towers of gravel capped by stones 1431 01:21:17,706 --> 01:21:22,877 that stood guard over some of the mountain valleys. 1432 01:21:23,003 --> 01:21:26,255 To explain how the rocks arrived at these positions, 1433 01:21:26,381 --> 01:21:29,258 he speculated that they had been carried and deposited 1434 01:21:29,384 --> 01:21:33,345 by ancient glaciers that had once filled the Alpine valleys 1435 01:21:33,471 --> 01:21:37,474 and covered the Northern Hemisphere. 1436 01:21:37,601 --> 01:21:39,810 lnitially ridiculed by his peers, 1437 01:21:39,936 --> 01:21:42,521 Agassiz's ice age theory became accepted 1438 01:21:42,647 --> 01:21:45,274 as telltale signs that these huge glaciers 1439 01:21:45,400 --> 01:21:47,401 had indeed covered the continents 1440 01:21:47,527 --> 01:21:50,946 were found all over the globe. 1441 01:21:51,072 --> 01:21:53,240 The evidence is everywhere. 1442 01:22:00,790 --> 01:22:03,125 New York's Central Park: 1443 01:22:03,251 --> 01:22:06,045 this oasis of green in the middle of Manhattan 1444 01:22:06,171 --> 01:22:09,632 exposes part of the island's ancient bedrock. 1445 01:22:09,758 --> 01:22:12,259 Many large outcrops are visible, 1446 01:22:12,385 --> 01:22:15,387 and they contain the footprints of the glaciers. 1447 01:22:19,476 --> 01:22:21,393 Climate expert Joerg Schaefer 1448 01:22:21,519 --> 01:22:25,689 is looking for subtle traces of this frozen world. 1449 01:22:25,815 --> 01:22:27,316 - lt's actually something l bet 1450 01:22:27,442 --> 01:22:28,776 that most New Yorkers do not know. 1451 01:22:28,902 --> 01:22:30,361 You see the ice age is everywhere 1452 01:22:30,487 --> 01:22:33,238 if you open your eyes. 1453 01:22:33,365 --> 01:22:37,159 narrator: Look closely, and the superhard bedrock 1454 01:22:37,285 --> 01:22:40,996 is marked with scores of tiny parallel lines 1455 01:22:41,122 --> 01:22:43,540 fractions of an inch deep. 1456 01:22:43,667 --> 01:22:47,336 - So this point here is actually one of the most amazing spots 1457 01:22:47,462 --> 01:22:50,965 of evidence for an ice age in the middle of New York City. 1458 01:22:51,091 --> 01:22:53,842 narrator: The grooves were caused by small rocks 1459 01:22:53,969 --> 01:22:57,471 caught under the massive weight of a moving glacier. 1460 01:22:57,597 --> 01:22:59,848 - These little rocks basically cut like a knife 1461 01:22:59,975 --> 01:23:02,935 into this very hard bedrock. 1462 01:23:03,061 --> 01:23:05,312 This is clear proof that, once, 1463 01:23:05,438 --> 01:23:08,023 an enormous ice sheet was moving in this direction 1464 01:23:08,149 --> 01:23:10,150 in the middle of New York City. 1465 01:23:14,656 --> 01:23:19,076 narrator: The glaciers that hit New York were massive. 1466 01:23:19,202 --> 01:23:20,869 They rolled down from the Arctic 1467 01:23:20,996 --> 01:23:25,708 and buried Manhattan under a huge depth of ice. 1468 01:23:25,834 --> 01:23:27,584 - To give you an idea about the thickness 1469 01:23:27,711 --> 01:23:30,879 of the Laurentide ice sheet in the Manhattan area, 1470 01:23:31,006 --> 01:23:33,424 it was at least twice as thick 1471 01:23:33,550 --> 01:23:36,093 as the Empire State Building is high today. 1472 01:23:36,219 --> 01:23:39,054 narrator: Over the last 2 million years, 1473 01:23:39,180 --> 01:23:41,682 as the climate fluctuated, 1474 01:23:41,808 --> 01:23:46,228 the huge ice sheets waxed and waned. 1475 01:23:46,354 --> 01:23:49,023 With every pass, they gouged and crushed 1476 01:23:49,149 --> 01:23:51,942 and reshaped the land beneath them. 1477 01:23:54,320 --> 01:23:58,407 As the last glaciers retreated 1 0,000 years ago, 1478 01:23:58,533 --> 01:24:01,618 they left behind a bruised and battered landscape 1479 01:24:01,745 --> 01:24:06,790 and created features we still see today. 1480 01:24:06,916 --> 01:24:09,418 ln the U.S.A., Cape Cod and Long lsland 1481 01:24:09,544 --> 01:24:11,628 are built on immense piles of boulders 1482 01:24:11,755 --> 01:24:16,759 dropped from the retreating edge of the North American ice sheet. 1483 01:24:16,885 --> 01:24:20,387 And the great weight of the ice formed huge depressions 1484 01:24:20,513 --> 01:24:23,140 that now make up the Great Lakes. 1485 01:24:23,266 --> 01:24:24,850 ln the warmer climate 1486 01:24:24,976 --> 01:24:27,352 that followed the last glacial retreat, 1487 01:24:27,479 --> 01:24:34,985 early humans had free reign over the surface. 1488 01:24:35,111 --> 01:24:39,573 ln this brief period, a fraction of a fraction of 1% 1489 01:24:39,699 --> 01:24:41,742 of the history of the Earth, 1490 01:24:41,868 --> 01:24:47,122 the entire history of human civilization has taken place. 1491 01:24:47,248 --> 01:24:50,793 Human ingenuity has reshaped our planet. 1492 01:24:50,919 --> 01:24:52,669 From our perspective, 1493 01:24:52,796 --> 01:24:56,590 our achievements are breathtaking. 1494 01:24:56,716 --> 01:25:00,552 But will we continue to survive and prosper? 1495 01:25:00,678 --> 01:25:02,554 - Humans have, with technology, 1496 01:25:02,680 --> 01:25:05,265 dominated the planet more completely, perhaps, 1497 01:25:05,391 --> 01:25:08,143 than any other animal in the history of life, 1498 01:25:08,269 --> 01:25:10,646 but we've done it for such a short period of time 1499 01:25:10,772 --> 01:25:13,649 that we've got a long ways to go. 1500 01:25:13,775 --> 01:25:16,652 narrator: Over the past 4.5 billion years, 1501 01:25:16,778 --> 01:25:20,322 the Earth has been on the most incredible journey. 1502 01:25:20,448 --> 01:25:24,243 Over the eons of its existence, the planetary environment 1503 01:25:24,369 --> 01:25:28,664 has undergone immense transformations. 1504 01:25:28,790 --> 01:25:30,874 And since the arrival of life, 1505 01:25:31,000 --> 01:25:33,502 these transformations have in many ways 1506 01:25:33,628 --> 01:25:37,506 determined which organisms will survive 1507 01:25:37,632 --> 01:25:42,177 and which will be swept aside. 1508 01:25:42,303 --> 01:25:45,389 lf this turbulent past is any guide to the future, 1509 01:25:45,515 --> 01:25:47,349 life and humans in particular 1510 01:25:47,475 --> 01:25:50,018 will face further battles for survival 1511 01:25:50,145 --> 01:25:54,189 as the planet continues along its path of change. 1512 01:25:54,315 --> 01:25:56,692 - Life is highly dependent on the Earth. 1513 01:25:56,818 --> 01:26:01,530 What the Earth gives us is what we have to deal with. 1514 01:26:01,656 --> 01:26:04,158 - lt's hard to separate completely 1515 01:26:04,284 --> 01:26:07,870 the processes of geology and the processes of life. 1516 01:26:07,996 --> 01:26:11,665 Life in some ways drives geology, 1517 01:26:11,791 --> 01:26:13,667 and geology creates the environments 1518 01:26:13,793 --> 01:26:17,171 in which life thrives. 1519 01:26:17,297 --> 01:26:22,384 narrator: Our first major challenge will be the climate. 1520 01:26:22,510 --> 01:26:24,553 At the start of the 21st century, 1521 01:26:24,679 --> 01:26:27,181 we may worry about global warming, 1522 01:26:27,307 --> 01:26:29,057 but most scientists recognize 1523 01:26:29,184 --> 01:26:32,561 that we are in a gap between ice ages. 1524 01:26:32,687 --> 01:26:34,897 Our whole civilization has occurred 1525 01:26:35,023 --> 01:26:39,318 in a brief warm period, 1 0,000 years so far. 1526 01:26:39,444 --> 01:26:42,279 This warmth has proved crucial. 1527 01:26:42,405 --> 01:26:43,864 - lt's definitely not a coincidence 1528 01:26:43,990 --> 01:26:46,909 that civilizations developed over this period of time, 1529 01:26:47,035 --> 01:26:49,912 because the climate is so favorable to our species 1530 01:26:50,038 --> 01:26:52,289 to develop and flourish. 1531 01:26:52,415 --> 01:26:54,958 The period we live in the moment climate-wise 1532 01:26:55,084 --> 01:26:57,044 over the last, let's say, 1 0,000 years 1533 01:26:57,170 --> 01:26:59,296 is exceptionally stable. 1534 01:26:59,422 --> 01:27:01,215 lt's almost unbelievably stable 1535 01:27:01,341 --> 01:27:03,425 if you look into the geological record. 1536 01:27:03,551 --> 01:27:06,470 lt certainly will not stay forever like that. 1537 01:27:06,596 --> 01:27:08,430 narrator: Even if our industrial economies 1538 01:27:08,556 --> 01:27:09,806 effect a global warming 1539 01:27:09,933 --> 01:27:11,600 over the next couple of centuries, 1540 01:27:11,726 --> 01:27:14,269 they can do no more than delay the inevitable. 1541 01:27:14,395 --> 01:27:16,063 The continents' current positions 1542 01:27:16,189 --> 01:27:17,940 keeping the polar oceans cool 1543 01:27:18,066 --> 01:27:23,403 mean that in just 1 5,000 years, a new ice age may occur. 1544 01:27:23,529 --> 01:27:27,824 - The New York area is going to be completely changed 1545 01:27:27,951 --> 01:27:29,952 by the next cycle of glaciation, 1546 01:27:30,078 --> 01:27:32,412 and at some point, glaciers are going to move down 1547 01:27:32,538 --> 01:27:37,417 and grind New York into the North Atlantic Ocean. 1548 01:27:39,837 --> 01:27:42,798 narrator: But even if we survive the big freezes, 1549 01:27:42,924 --> 01:27:45,509 there will be greater challenges to come. 1550 01:27:45,635 --> 01:27:47,970 As plate tectonics move the continents 1551 01:27:48,096 --> 01:27:49,721 and end the ice ages, 1552 01:27:49,847 --> 01:27:51,807 coastal regions will be engulfed, 1553 01:27:51,933 --> 01:27:56,520 and whole countries will disappear. 1554 01:27:56,646 --> 01:27:59,314 200 million years from now, 1555 01:27:59,440 --> 01:28:03,151 a new supercontinent, Pangaea Ultima, 1556 01:28:03,278 --> 01:28:04,861 is due to take shape 1557 01:28:04,988 --> 01:28:09,449 as first the Mediterranean and then the Atlantic Ocean 1558 01:28:09,575 --> 01:28:11,618 are swallowed up. 1559 01:28:11,744 --> 01:28:14,538 - There will be continents eventually colliding 1560 01:28:14,664 --> 01:28:16,498 with the east coast of North America, 1561 01:28:16,624 --> 01:28:19,543 so New York, in the long run, will be destroyed 1562 01:28:19,669 --> 01:28:21,712 in a continent-to-continent collision 1563 01:28:21,838 --> 01:28:25,007 and will be completely crushed 1564 01:28:25,133 --> 01:28:27,843 and thrust upward as a new mountain range. 1565 01:28:27,969 --> 01:28:29,803 narrator: The Earth will once again 1566 01:28:29,929 --> 01:28:32,389 be thrown into deadly turmoil. 1567 01:28:32,515 --> 01:28:34,599 Oxygen levels and surface temperatures 1568 01:28:34,726 --> 01:28:36,226 could fluctuate wildly 1569 01:28:36,352 --> 01:28:38,729 and lead to new mass extinctions. 1570 01:28:38,855 --> 01:28:41,606 But even the trauma of supercontinental disruption 1571 01:28:41,733 --> 01:28:44,067 is nothing compared to what will follow. 1572 01:28:44,193 --> 01:28:45,944 Everything will grind to a halt 1573 01:28:46,070 --> 01:28:50,574 when the plate-tectonic engine finally stops. 1574 01:28:50,700 --> 01:28:53,327 - The maintenance of habitability on this planet 1575 01:28:53,453 --> 01:28:57,706 is involved with the plate-tectonic cycle. 1576 01:28:57,832 --> 01:29:00,375 lt's not an infinite cycle. 1577 01:29:00,501 --> 01:29:02,044 There is an end in sight. 1578 01:29:02,170 --> 01:29:03,462 lt's billions of years from now, 1579 01:29:03,588 --> 01:29:05,881 but we know, eventually, the system will wear out. 1580 01:29:06,007 --> 01:29:07,758 narrator: The fires in the depths 1581 01:29:07,884 --> 01:29:10,218 that have dominated activity on the surface 1582 01:29:10,345 --> 01:29:13,055 will one day use up their fuel, 1583 01:29:13,181 --> 01:29:19,895 and the story of planet Earth will be over. 1584 01:29:20,021 --> 01:29:22,939 Without its burning heart, the Earth will share 1585 01:29:23,066 --> 01:29:26,026 what many believe was the fate of Mars. 1586 01:29:28,321 --> 01:29:31,239 The atmosphere and oceans will be stripped away, 1587 01:29:31,366 --> 01:29:35,202 and the surface will become a bone-dry barren desert. 1588 01:29:35,328 --> 01:29:38,205 The planet will be dead. 1589 01:29:41,209 --> 01:29:45,128 But this is a picture of an incredibly distant future. 1590 01:29:45,254 --> 01:29:47,422 For at least the next billion years, 1591 01:29:47,548 --> 01:29:50,092 as the Earth continues its epicjourney, 1592 01:29:50,218 --> 01:29:54,054 some form of life should continue. 1593 01:29:55,556 --> 01:29:58,642 But the human species, which has walked the Earth 1594 01:29:58,768 --> 01:30:00,685 for over 2 million years 1595 01:30:00,812 --> 01:30:03,730 and mastered it only in the last 1 0,000, 1596 01:30:03,856 --> 01:30:05,440 may be in danger. 1597 01:30:05,566 --> 01:30:08,151 As the environment transforms, 1598 01:30:08,277 --> 01:30:11,738 Earth could well become unfit for humans. 1599 01:30:11,864 --> 01:30:14,199 lf that happens in the distant future, 1600 01:30:14,325 --> 01:30:16,535 rather than be forced to face extinction 1601 01:30:16,661 --> 01:30:18,412 like our predecessors, 1602 01:30:18,538 --> 01:30:21,123 technology may allow us to leave Earth 1603 01:30:21,249 --> 01:30:23,792 in search of new homes, 1604 01:30:23,918 --> 01:30:28,588 other blue-green planets on which to make a new start, 127338

Can't find what you're looking for?
Get subtitles in any language from opensubtitles.com, and translate them here.