1 00:00:00,000 --> 00:00:04,162 WWW.MY-SUBS.CO 1 00:00:02,489 --> 00:00:05,892 >> Earth, a unique planet, 2 00:00:05,926 --> 00:00:10,196 restless and dynamic. 3 00:00:10,264 --> 00:00:13,032 Continents shift and clash, 4 00:00:13,100 --> 00:00:15,535 volcanoes erupt, 5 00:00:15,569 --> 00:00:18,371 glaciers grow and recede-- 6 00:00:18,439 --> 00:00:19,939 titanic forces that are 7 00:00:20,007 --> 00:00:21,908 constantly at work, 8 00:00:21,942 --> 00:00:22,942 leaving a trail 9 00:00:23,010 --> 00:00:27,647 of geological mysteries behind. 10 00:00:27,714 --> 00:00:29,382 And there is nowhere more 11 00:00:29,483 --> 00:00:32,185 mysterious than Death Valley, 12 00:00:32,286 --> 00:00:34,754 the hottest and driest desert 13 00:00:34,822 --> 00:00:38,024 in the United States. 14 00:00:38,092 --> 00:00:39,759 This is a place where even 15 00:00:39,827 --> 00:00:43,196 700-pound rocks appear to move 16 00:00:43,297 --> 00:00:46,999 by themselves. 17 00:00:47,101 --> 00:00:48,000 It's the lowest point 18 00:00:48,102 --> 00:00:50,837 in the U.S., and right here, 19 00:00:50,904 --> 00:00:52,338 the earth's crust is thinner 20 00:00:52,372 --> 00:00:54,073 than almost anywhere else 21 00:00:54,108 --> 00:00:56,843 on the planet. 22 00:00:56,910 --> 00:00:58,344 Death Valley is a dynamic 23 00:00:58,378 --> 00:01:00,480 laboratory for investigators 24 00:01:00,547 --> 00:01:02,281 who uniquely read rocks 25 00:01:02,349 --> 00:01:04,383 like x-rays to reveal 26 00:01:04,451 --> 00:01:06,519 the inner workings of the Earth 27 00:01:06,553 --> 00:01:09,822 and its history... 28 00:01:09,890 --> 00:01:12,058 adding to the continuing story 29 00:01:12,059 --> 00:01:15,594 S02x09 Death Valley Original Air Date on January 26, 2010 30 00:01:15,663 --> 00:01:19,231 -- Sync, corrected by elderman -- -- for MY-SUBS.com --- 31 00:01:22,803 --> 00:01:24,504 Death Valley is the largest 32 00:01:24,538 --> 00:01:26,405 National Park in the lower 48 33 00:01:26,440 --> 00:01:29,075 states, more than 3 times 34 00:01:29,143 --> 00:01:32,612 the size of Rhode Island, 35 00:01:32,679 --> 00:01:33,412 straddling the border 36 00:01:33,447 --> 00:01:35,581 of California and Nevada 37 00:01:35,649 --> 00:01:36,916 and surrounded by towering 38 00:01:36,950 --> 00:01:40,386 mountain peaks. 39 00:01:40,487 --> 00:01:42,488 140 miles long 40 00:01:42,589 --> 00:01:45,124 and up to 15 miles wide, 41 00:01:45,225 --> 00:01:46,225 with temperatures reaching 42 00:01:46,293 --> 00:01:48,861 a scorching 134 degrees 43 00:01:48,929 --> 00:01:50,830 fahrenheit, this is one 44 00:01:50,931 --> 00:01:52,932 of the most inhospitable places 45 00:01:53,000 --> 00:01:54,400 on Earth. 46 00:01:54,468 --> 00:01:57,670 [rattlesnake hissing] 47 00:01:57,738 --> 00:01:59,939 But for geologists, Death Valley 48 00:02:00,040 --> 00:02:01,807 has a unique attraction. 49 00:02:01,842 --> 00:02:03,376 Here they can witness 50 00:02:03,410 --> 00:02:04,577 the interplay of the Earth's 51 00:02:04,678 --> 00:02:09,649 most titanic geological forces. 52 00:02:09,750 --> 00:02:10,383 >> When you look at Death 53 00:02:10,450 --> 00:02:12,018 Valley, really you're looking 54 00:02:12,019 --> 00:02:14,387 at a battle, a battle between 55 00:02:14,488 --> 00:02:15,855 processes that are occurring 56 00:02:15,923 --> 00:02:17,290 on the earth's surface, 57 00:02:17,291 --> 00:02:18,658 and we can see the record 58 00:02:18,725 --> 00:02:20,026 of those forces of nature 59 00:02:20,127 --> 00:02:21,994 locked into the rocks. 60 00:02:22,029 --> 00:02:24,263 Death Valley has an archive 61 00:02:24,298 --> 00:02:25,665 that is almost unrivaled 62 00:02:25,666 --> 00:02:28,334 worldwide. 63 00:02:28,368 --> 00:02:29,902 >> To uncover Death Valley's 64 00:02:29,970 --> 00:02:31,704 earliest history, Prave is 65 00:02:31,805 --> 00:02:33,906 hunting for its oldest rocks. 66 00:02:37,311 --> 00:02:38,511 He is searching in one 67 00:02:38,579 --> 00:02:40,947 of its most remote spots, 68 00:02:41,014 --> 00:02:42,481 in the extreme south 69 00:02:42,516 --> 00:02:44,917 of the valley in the isolated 70 00:02:44,952 --> 00:02:48,287 Alexander hills. 71 00:02:48,322 --> 00:02:49,388 >> This is one of the oldest 72 00:02:49,489 --> 00:02:50,656 rocks in Death Valley. 73 00:02:50,691 --> 00:02:52,391 It's 1.2 billion years old. 74 00:02:52,492 --> 00:02:54,126 And given the color of this rock 75 00:02:54,228 --> 00:02:55,094 and the fact that it's 76 00:02:55,128 --> 00:02:56,395 quite soft--it can powder 77 00:02:56,463 --> 00:02:57,964 when I scratch it-- 78 00:02:58,031 --> 00:02:59,932 These are all clues that tell me 79 00:02:59,967 --> 00:03:02,668 that this is a limestone. 80 00:03:02,769 --> 00:03:04,570 >> The limestone is a major clue 81 00:03:04,671 --> 00:03:05,571 to revealing the way 82 00:03:05,672 --> 00:03:10,109 this arid desert used to look. 83 00:03:10,143 --> 00:03:11,410 >> If we think about the type 84 00:03:11,478 --> 00:03:13,579 of environments that limestones 85 00:03:13,680 --> 00:03:15,014 can be deposited in, 86 00:03:15,048 --> 00:03:16,549 the first that comes to mind 87 00:03:16,583 --> 00:03:17,316 is an underwater 88 00:03:17,384 --> 00:03:19,318 and a marine setting. 89 00:03:21,588 --> 00:03:22,955 >> There is only one way 90 00:03:23,023 --> 00:03:24,757 to form limestone. 91 00:03:24,825 --> 00:03:26,459 It is made from the tiny bones 92 00:03:26,493 --> 00:03:28,861 and shells of sea creatures. 93 00:03:28,929 --> 00:03:30,763 They die and sink to the sea 94 00:03:30,864 --> 00:03:32,365 floor, where the weight 95 00:03:32,366 --> 00:03:34,367 of further layers on top of them 96 00:03:34,468 --> 00:03:35,601 crushes them slowly 97 00:03:35,636 --> 00:03:37,603 into solid rock. 98 00:03:42,743 --> 00:03:44,277 And Prave has discovered 99 00:03:44,378 --> 00:03:45,911 other startling evidence 100 00:03:45,979 --> 00:03:47,079 that Death Valley had 101 00:03:47,147 --> 00:03:49,181 a watery past. 102 00:03:49,249 --> 00:03:51,817 >> Fossils are a major clue. 103 00:03:51,918 --> 00:03:54,053 They are vital in the type 104 00:03:54,087 --> 00:03:55,421 of evidence that a geologist 105 00:03:55,455 --> 00:03:57,123 will use. And these are 106 00:03:57,157 --> 00:03:58,491 some very nice examples 107 00:03:58,592 --> 00:03:59,792 of the type of fossils 108 00:03:59,860 --> 00:04:00,559 that you can find 109 00:04:00,594 --> 00:04:03,696 in these ancient rocks. 110 00:04:03,764 --> 00:04:04,563 And you can see here 111 00:04:04,598 --> 00:04:06,499 these curving surfaces 112 00:04:06,600 --> 00:04:09,135 outlining what look to be 113 00:04:09,202 --> 00:04:10,503 large cabbages that are 114 00:04:10,604 --> 00:04:12,038 sliced in half. 115 00:04:12,105 --> 00:04:13,205 These were algae 116 00:04:13,240 --> 00:04:15,975 known as a stromatolite. 117 00:04:16,043 --> 00:04:17,610 >> Ironically, these marine 118 00:04:17,678 --> 00:04:18,878 fossils have survived 119 00:04:18,945 --> 00:04:20,246 in the Death Valley desert 120 00:04:20,314 --> 00:04:21,314 only because there is 121 00:04:21,381 --> 00:04:22,782 so little water that might 122 00:04:22,883 --> 00:04:27,787 otherwise have washed them away. 123 00:04:27,854 --> 00:04:29,422 But they would have originally 124 00:04:29,489 --> 00:04:31,490 looked like this 125 00:04:31,558 --> 00:04:32,491 when they flourished 126 00:04:32,592 --> 00:04:34,060 in the Death Valley waters 127 00:04:34,127 --> 00:04:35,594 as the limestone formed 128 00:04:35,662 --> 00:04:38,831 more than one billion years ago. 129 00:04:38,865 --> 00:04:39,665 >> These tell us that 130 00:04:39,700 --> 00:04:41,200 the environment when this rock 131 00:04:41,234 --> 00:04:42,234 formed would have been 132 00:04:42,336 --> 00:04:44,503 a shallow sea. 133 00:04:44,571 --> 00:04:46,372 If I'd been here when these 134 00:04:46,406 --> 00:04:48,140 rocks were first being formed, 135 00:04:48,241 --> 00:04:49,675 I'd be sitting in my swimming 136 00:04:49,776 --> 00:04:50,776 trunks about waist-deep 137 00:04:50,844 --> 00:04:52,011 in water, very much 138 00:04:52,045 --> 00:04:55,214 like the Bahamas today. 139 00:04:55,282 --> 00:04:56,148 >> The stromatolites are 140 00:04:56,216 --> 00:04:57,583 some of the earliest signs 141 00:04:57,651 --> 00:05:00,319 of life on our planet. 142 00:05:00,387 --> 00:05:01,654 To discover what happened 143 00:05:01,688 --> 00:05:04,056 over the next one billion years, 144 00:05:04,124 --> 00:05:05,691 Prave studies evidence 145 00:05:05,759 --> 00:05:08,694 in the surrounding hills. 146 00:05:08,762 --> 00:05:10,396 >> The different bands of colors 147 00:05:10,497 --> 00:05:12,465 and the rock layers in the hills 148 00:05:12,499 --> 00:05:13,966 represent ancient seas that 149 00:05:14,034 --> 00:05:15,768 covered the Death Valley area. 150 00:05:15,836 --> 00:05:17,236 The seas would deposit 151 00:05:17,304 --> 00:05:18,738 a layer of limestone, 152 00:05:18,772 --> 00:05:20,139 move back across the land. 153 00:05:20,207 --> 00:05:21,407 Another layer of limestone 154 00:05:21,475 --> 00:05:22,641 would be deposited. 155 00:05:22,676 --> 00:05:23,576 And so we have a history 156 00:05:23,677 --> 00:05:25,678 of the seas moving across 157 00:05:25,746 --> 00:05:27,113 the Death Valley region from 158 00:05:27,214 --> 00:05:28,581 the time of the stromatolites 159 00:05:28,682 --> 00:05:30,216 to these rock layers now, 160 00:05:30,283 --> 00:05:34,854 more than a billion years later. 161 00:05:34,921 --> 00:05:35,955 >> Geologists wanted to 162 00:05:36,022 --> 00:05:37,390 figure out what dramatic 163 00:05:37,491 --> 00:05:38,958 geological upheaval could 164 00:05:39,025 --> 00:05:40,459 have turned Death Valley 165 00:05:40,494 --> 00:05:41,927 from a shallow sea to the 166 00:05:42,028 --> 00:05:45,865 baking-hot desert of today. 167 00:05:45,932 --> 00:05:47,566 And Prave has found clues 168 00:05:47,667 --> 00:05:49,402 in a rock that is entirely 169 00:05:49,503 --> 00:05:50,669 different from the marine 170 00:05:50,737 --> 00:05:52,204 limestones he has studied 171 00:05:52,272 --> 00:05:55,474 up until now. 172 00:05:55,542 --> 00:05:56,909 >> This is a nice example 173 00:05:57,010 --> 00:05:59,545 of a rock type called a granite. 174 00:05:59,579 --> 00:06:02,014 And it forms those veins that 175 00:06:02,048 --> 00:06:05,551 are in the hillside behind me. 176 00:06:05,585 --> 00:06:06,819 You can think of these 177 00:06:06,853 --> 00:06:08,654 like the fingers of my hand. 178 00:06:08,722 --> 00:06:09,955 They're fed upward from 179 00:06:10,023 --> 00:06:11,824 a much more larger, massive area 180 00:06:11,858 --> 00:06:15,027 of granite sitting underneath. 181 00:06:15,128 --> 00:06:16,996 >> The granite tells scientists 182 00:06:17,030 --> 00:06:18,664 the reasons why Death Valley's 183 00:06:18,732 --> 00:06:22,201 ancient seas vanished. 184 00:06:22,269 --> 00:06:24,904 Today, it is solid rock. 185 00:06:24,938 --> 00:06:27,306 But it was once hot molten magma 186 00:06:27,407 --> 00:06:31,310 from deep underground. 187 00:06:31,378 --> 00:06:33,012 Only one force of nature 188 00:06:33,079 --> 00:06:34,647 has the awesome power 189 00:06:34,681 --> 00:06:37,383 and 2,000-degree fahrenheit heat 190 00:06:37,484 --> 00:06:39,652 to melt rock into magma 191 00:06:39,719 --> 00:06:41,654 and fire it to the surface... 192 00:06:44,825 --> 00:06:48,661 Volcanoes. 193 00:06:48,728 --> 00:06:49,728 The seas here didn't 194 00:06:49,763 --> 00:06:51,664 just drain away. 195 00:06:51,765 --> 00:06:53,032 They were pushed back 196 00:06:53,099 --> 00:06:55,100 by these mountains of fire. 197 00:07:01,675 --> 00:07:03,676 It was only in the 1960s, 198 00:07:03,743 --> 00:07:04,543 with the realization 199 00:07:04,644 --> 00:07:05,744 that earth's continents 200 00:07:05,812 --> 00:07:07,847 were drifting around the planet, 201 00:07:07,914 --> 00:07:09,281 that scientists figured out 202 00:07:09,349 --> 00:07:11,116 why the volcanoes erupted 203 00:07:11,218 --> 00:07:14,753 under Death Valley. 204 00:07:14,821 --> 00:07:16,755 The theory of plate tectonics 205 00:07:16,823 --> 00:07:17,823 revealed that around 206 00:07:17,924 --> 00:07:19,825 100 million years ago, 207 00:07:19,926 --> 00:07:21,827 an ancient oceanic plate began 208 00:07:21,895 --> 00:07:24,029 sinking under North America, 209 00:07:24,097 --> 00:07:27,833 pushing up the land. 210 00:07:27,934 --> 00:07:29,301 Heat from the collision powered 211 00:07:29,369 --> 00:07:32,104 a coastal chain of volcanoes, 212 00:07:32,172 --> 00:07:34,306 erupting on the land and finally 213 00:07:34,374 --> 00:07:35,908 driving away the seas 214 00:07:35,942 --> 00:07:38,177 submerging Death Valley. 215 00:07:38,211 --> 00:07:39,211 >> This landscape would have 216 00:07:39,279 --> 00:07:42,014 been very explosive, a hostile 217 00:07:42,082 --> 00:07:43,349 type of setting. 218 00:07:43,383 --> 00:07:45,484 And that then set the stage 219 00:07:45,552 --> 00:07:46,886 for what was to become 220 00:07:46,920 --> 00:07:50,756 Death Valley. 221 00:07:50,824 --> 00:07:52,458 >> Still surviving in the valley 222 00:07:52,526 --> 00:07:54,193 to this day is the ghost-town 223 00:07:54,294 --> 00:07:56,362 evidence of another substance 224 00:07:56,463 --> 00:07:58,464 far rarer than granite 225 00:07:58,565 --> 00:07:59,632 that the volcanoes 226 00:07:59,666 --> 00:08:03,369 grought to the surface... 227 00:08:03,470 --> 00:08:06,906 gold. 228 00:08:06,973 --> 00:08:08,841 Although gold occurs naturally 229 00:08:08,909 --> 00:08:10,209 in more than 30 different 230 00:08:10,277 --> 00:08:12,378 U.S. States, the gold 231 00:08:12,479 --> 00:08:14,280 in Death Valley was concentrated 232 00:08:14,347 --> 00:08:16,749 in veins in the rock, as magma 233 00:08:16,816 --> 00:08:19,184 solidified near the surface. 234 00:08:19,252 --> 00:08:20,920 It made it worth mining, 235 00:08:20,987 --> 00:08:21,921 and millions of years 236 00:08:22,022 --> 00:08:24,156 after its formation, it sparked 237 00:08:24,190 --> 00:08:26,926 the Death Valley gold rush. 238 00:08:26,993 --> 00:08:28,294 >> This is a wonderful example 239 00:08:28,361 --> 00:08:30,162 of a gold mine shaft. 240 00:08:30,196 --> 00:08:32,097 It's the Eureka mine, high up 241 00:08:32,198 --> 00:08:33,632 in the Panamint Mountains, 242 00:08:33,700 --> 00:08:35,634 associated with trying to find 243 00:08:35,735 --> 00:08:38,003 gold in the granites that were 244 00:08:38,104 --> 00:08:39,738 intruded into these rocks 245 00:08:39,806 --> 00:08:42,875 100 to 200 million years ago. 246 00:08:42,909 --> 00:08:44,176 The gold would have been 247 00:08:44,244 --> 00:08:45,644 in veins, these fingers 248 00:08:45,745 --> 00:08:46,645 that would have been injected 249 00:08:46,746 --> 00:08:48,280 up into these rocks. 250 00:08:48,381 --> 00:08:49,648 And the gold would have been 251 00:08:49,716 --> 00:08:51,650 concentrated in these veins. 252 00:08:55,355 --> 00:08:57,056 >> The gold rush here lasted 253 00:08:57,090 --> 00:08:59,091 just a few years. 254 00:08:59,192 --> 00:09:00,559 Miners often had to remove 255 00:09:00,627 --> 00:09:02,361 a ton of rock to recover 256 00:09:02,429 --> 00:09:04,897 only 1/10th of an ounce of gold, 257 00:09:04,998 --> 00:09:06,632 enough to produce just a single 258 00:09:06,733 --> 00:09:10,869 wedding ring. 259 00:09:10,904 --> 00:09:12,438 Today, all that remains are 260 00:09:12,539 --> 00:09:18,444 empty tunnels and ghost towns. 261 00:09:18,511 --> 00:09:19,712 >> It's interesting to consider 262 00:09:19,813 --> 00:09:22,348 that the frenzy of activity, 263 00:09:22,449 --> 00:09:24,650 mining gold, was actually 264 00:09:24,718 --> 00:09:26,986 a direct result of the kind 265 00:09:27,053 --> 00:09:28,721 of volcanic activity 266 00:09:28,822 --> 00:09:31,991 100 to 200 million years ago. 267 00:09:32,092 --> 00:09:33,459 >> Geologists investigating 268 00:09:33,526 --> 00:09:34,693 the battle that raged 269 00:09:34,728 --> 00:09:36,462 in Death Valley between fiery 270 00:09:36,529 --> 00:09:39,164 volcanoes and ancient seas 271 00:09:39,232 --> 00:09:41,500 have found important evidence. 272 00:09:44,537 --> 00:09:46,605 Stromatolite fossils are proof 273 00:09:46,640 --> 00:09:48,007 that Death Valley was once 274 00:09:48,074 --> 00:09:49,608 submerged by the waters 275 00:09:49,643 --> 00:09:52,277 of a shallow sea. 276 00:09:52,345 --> 00:09:53,979 Veins of granite could only 277 00:09:54,047 --> 00:09:55,614 have formed in the fiery heat 278 00:09:55,715 --> 00:09:57,249 of the volcanoes that burst 279 00:09:57,317 --> 00:09:58,617 to the surface around 280 00:09:58,718 --> 00:10:00,552 100 million years ago 281 00:10:00,620 --> 00:10:03,989 and drove that sea away. 282 00:10:04,057 --> 00:10:05,691 The volcanoes built up the land 283 00:10:05,725 --> 00:10:07,259 that was to become Death Valley 284 00:10:07,360 --> 00:10:08,594 into peaks as high 285 00:10:08,628 --> 00:10:11,363 as the Cascades Mountain range. 286 00:10:11,431 --> 00:10:12,631 But deep beneath the Earth's 287 00:10:12,732 --> 00:10:14,967 surface, awesome geological 288 00:10:15,001 --> 00:10:16,635 forces were about to destroy 289 00:10:16,703 --> 00:10:20,072 those peaks, stretch the land 290 00:10:20,173 --> 00:10:21,974 apart, and transform 291 00:10:22,075 --> 00:10:23,976 the mountains of Death Valley 292 00:10:24,077 --> 00:10:25,611 into the lowest point 293 00:10:25,712 --> 00:10:27,613 in the U.S. 294 00:10:29,836 --> 00:10:31,270 >> For a billion years, 295 00:10:31,371 --> 00:10:32,604 Death Valley remained 296 00:10:32,639 --> 00:10:36,708 a flat plain under the sea. 297 00:10:36,743 --> 00:10:38,610 Around 100 million years ago, 298 00:10:38,645 --> 00:10:40,379 erupting volcanoes formed 299 00:10:40,446 --> 00:10:43,548 high mountain ranges. 300 00:10:43,650 --> 00:10:45,651 But then the real geological 301 00:10:45,718 --> 00:10:48,453 mystery began. The land here 302 00:10:48,521 --> 00:10:49,554 must have undergone 303 00:10:49,622 --> 00:10:52,357 an extraordinary transformation 304 00:10:52,425 --> 00:10:54,893 because today in Death Valley, 305 00:10:54,994 --> 00:10:56,194 those high mountain ranges 306 00:10:56,262 --> 00:10:58,830 have vanished. Incredibly, 307 00:10:58,898 --> 00:11:00,098 the one-time mountains 308 00:11:00,166 --> 00:11:02,100 have sunk below sea level 309 00:11:02,168 --> 00:11:04,069 to become the lowest point 310 00:11:04,103 --> 00:11:08,073 in North America. 311 00:11:08,174 --> 00:11:10,075 Yet all around the valley, 312 00:11:10,176 --> 00:11:12,077 snow-capped peaks still soar 313 00:11:12,178 --> 00:11:17,082 up to 11,000 feet into the air. 314 00:11:17,183 --> 00:11:18,817 The investigation digs deep 315 00:11:18,885 --> 00:11:20,552 under the landscape to discover 316 00:11:20,620 --> 00:11:22,988 what vast geological forces 317 00:11:23,056 --> 00:11:23,822 could have caused 318 00:11:23,890 --> 00:11:25,624 that huge difference in height 319 00:11:25,725 --> 00:11:27,726 between two places just 320 00:11:27,827 --> 00:11:31,363 20 miles away from each other. 321 00:11:31,431 --> 00:11:32,264 >> There are a lot of 322 00:11:32,332 --> 00:11:33,432 mysterious aspects 323 00:11:33,466 --> 00:11:34,800 about Death Valley. 324 00:11:34,867 --> 00:11:36,601 It's a unique landscape, 325 00:11:36,602 --> 00:11:38,370 because the valley floor itself 326 00:11:38,438 --> 00:11:39,805 is very deep. 327 00:11:39,906 --> 00:11:41,006 It's below sea level. 328 00:11:41,074 --> 00:11:42,541 And the mountains rise up 329 00:11:42,642 --> 00:11:45,911 very steeply on either side. 330 00:11:45,912 --> 00:11:46,979 >> Clues to the power 331 00:11:47,080 --> 00:11:48,613 of these underground forces 332 00:11:48,715 --> 00:11:50,816 lie all over the valley... 333 00:11:50,883 --> 00:11:54,987 If you know where to look. 334 00:11:55,054 --> 00:11:56,154 many of the rock layers 335 00:11:56,255 --> 00:11:57,723 were originally deposited 336 00:11:57,824 --> 00:12:00,359 on the ancient flat sea bed. 337 00:12:00,426 --> 00:12:01,727 they can still be seen 338 00:12:01,794 --> 00:12:06,498 as horizontal layers. 339 00:12:06,566 --> 00:12:07,866 But other nearby layers 340 00:12:07,967 --> 00:12:09,835 aren't horizontal at all. 341 00:12:09,869 --> 00:12:11,136 They tilt downwards 342 00:12:11,204 --> 00:12:13,138 into the ground. 343 00:12:17,110 --> 00:12:18,777 Miller finds a further clue 344 00:12:18,845 --> 00:12:20,746 of earth's power in the unusual 345 00:12:20,780 --> 00:12:23,148 shape of this cinder cone, 346 00:12:23,216 --> 00:12:25,017 a mound of ash and debris 347 00:12:25,051 --> 00:12:27,419 lying on Death Valley's floor. 348 00:12:27,487 --> 00:12:28,754 >> It looks like it's 349 00:12:28,821 --> 00:12:30,589 two cinder cones, but in fact 350 00:12:30,690 --> 00:12:31,957 it's really just one 351 00:12:32,025 --> 00:12:33,291 that's been pulled apart 352 00:12:33,326 --> 00:12:35,227 along a big fault zone. 353 00:12:39,132 --> 00:12:41,466 This has moved some 700 feet 354 00:12:41,501 --> 00:12:43,869 in some 700,000 years. 355 00:12:43,936 --> 00:12:45,637 So that's about a foot 356 00:12:45,671 --> 00:12:47,205 per thousand years, 357 00:12:47,273 --> 00:12:48,273 which sounds like it's 358 00:12:48,307 --> 00:12:50,008 really, really slow, but if you 359 00:12:50,043 --> 00:12:51,643 look at it over a great length 360 00:12:51,677 --> 00:12:53,945 of geologic time, you get 361 00:12:54,047 --> 00:12:55,647 quite a lot of slip. 362 00:12:55,681 --> 00:12:57,482 And give it even longer time, 363 00:12:57,550 --> 00:13:01,453 it will be offset even more. 364 00:13:01,487 --> 00:13:02,954 >> Miller's next challenge 365 00:13:03,022 --> 00:13:04,656 is explaining what is making 366 00:13:04,757 --> 00:13:07,592 the fault line move. 367 00:13:07,660 --> 00:13:08,860 For that, she studies 368 00:13:08,928 --> 00:13:10,929 other ancient rock formations 369 00:13:10,997 --> 00:13:12,664 whose jagged outline has given 370 00:13:12,732 --> 00:13:16,201 them the name turtlebacks. 371 00:13:16,302 --> 00:13:17,936 >> The turtlebacks are crucial 372 00:13:18,004 --> 00:13:20,305 to understanding Death Valley's 373 00:13:20,373 --> 00:13:23,108 early origins. They have so much 374 00:13:23,176 --> 00:13:25,577 of the record here, if you're 375 00:13:25,645 --> 00:13:27,312 willing to spend time 376 00:13:27,380 --> 00:13:30,749 to try to unravel it. 377 00:13:30,817 --> 00:13:32,284 >> The real clue lies in 378 00:13:32,318 --> 00:13:36,021 the rocks' distinctive texture. 379 00:13:36,122 --> 00:13:37,022 >> If you just take a look 380 00:13:37,090 --> 00:13:38,190 at this rock closely, 381 00:13:38,224 --> 00:13:39,224 you can see that it's 382 00:13:39,292 --> 00:13:41,259 very kind of strung out, 383 00:13:41,360 --> 00:13:43,728 very stringy. It tends to be 384 00:13:43,763 --> 00:13:46,898 pretty fine grained. 385 00:13:46,933 --> 00:13:48,467 >> This texture tells Miller 386 00:13:48,568 --> 00:13:51,570 where these rocks came from. 387 00:13:51,671 --> 00:13:52,938 >> We see evidence that these 388 00:13:53,039 --> 00:13:54,272 rocks were deformed, 389 00:13:54,307 --> 00:13:55,107 just like if you'd take 390 00:13:55,174 --> 00:13:56,108 a piece of plastic 391 00:13:56,209 --> 00:13:57,109 and were to heat it up, 392 00:13:57,210 --> 00:13:58,009 you could bend it. 393 00:13:58,044 --> 00:13:59,478 It's the same thing with rock. 394 00:13:59,545 --> 00:14:01,346 And so these rocks formed at 395 00:14:01,447 --> 00:14:03,348 high temperatures and pressures 396 00:14:03,416 --> 00:14:05,250 within the earth's crust 397 00:14:05,318 --> 00:14:06,985 at depths of about 10 miles 398 00:14:07,086 --> 00:14:09,888 or so, and they have since been 399 00:14:09,989 --> 00:14:13,792 brought to the earth's surface. 400 00:14:13,893 --> 00:14:15,427 >> Miller concluded that some 401 00:14:15,461 --> 00:14:17,362 overwhelming underground force 402 00:14:17,430 --> 00:14:18,797 must have raised the turtleback 403 00:14:18,865 --> 00:14:20,432 rocks to the surface 404 00:14:20,500 --> 00:14:21,700 and stretched them out 405 00:14:21,734 --> 00:14:23,335 like warm toffee 406 00:14:23,369 --> 00:14:28,540 as Death Valley formed. 407 00:14:28,608 --> 00:14:29,774 The final explanation 408 00:14:29,809 --> 00:14:30,876 of what happened here 409 00:14:30,910 --> 00:14:33,178 once again came back to the way 410 00:14:33,246 --> 00:14:34,613 continents drift around 411 00:14:34,714 --> 00:14:37,616 the globe. 412 00:14:37,717 --> 00:14:39,050 As the collision of the plates 413 00:14:39,085 --> 00:14:40,252 that had forced ancient 414 00:14:40,319 --> 00:14:41,987 volcanoes to the surface 415 00:14:42,054 --> 00:14:44,156 slowed down and ceased, 416 00:14:44,257 --> 00:14:45,624 the high mountains that once 417 00:14:45,691 --> 00:14:47,492 dominated the land were slowly 418 00:14:47,527 --> 00:14:49,161 pulled apart and tilted 419 00:14:49,228 --> 00:14:52,230 downwards. 420 00:14:52,265 --> 00:14:53,698 Gradually, as the underlying 421 00:14:53,799 --> 00:14:55,867 crust grew thinner and thinner, 422 00:14:55,902 --> 00:14:57,269 a deep basin formed 423 00:14:57,336 --> 00:15:00,805 between the mountain ranges. 424 00:15:00,907 --> 00:15:02,541 Death Valley is the most extreme 425 00:15:02,608 --> 00:15:04,242 example of what such stretching 426 00:15:04,343 --> 00:15:06,511 forces can do. 427 00:15:06,579 --> 00:15:08,513 By measuring seismic waves, 428 00:15:08,614 --> 00:15:10,582 scientists discovered that here 429 00:15:10,616 --> 00:15:11,683 the continental crust 430 00:15:11,717 --> 00:15:14,352 is just 16 miles thick. 431 00:15:14,420 --> 00:15:15,987 This might sound like a lot, 432 00:15:16,055 --> 00:15:17,255 but it is far thinner 433 00:15:17,323 --> 00:15:18,623 than almost anywhere else 434 00:15:18,691 --> 00:15:20,592 on the planet. 435 00:15:20,660 --> 00:15:21,860 Around the globe, 436 00:15:21,928 --> 00:15:23,395 the earth's continental crust 437 00:15:23,496 --> 00:15:26,231 averages 25 miles thick. 438 00:15:26,299 --> 00:15:27,866 It's strongest beneath 439 00:15:27,934 --> 00:15:29,501 the Himalayas. 440 00:15:29,569 --> 00:15:31,203 At 43 miles, thick enough 441 00:15:31,237 --> 00:15:32,304 to support the weight 442 00:15:32,405 --> 00:15:33,605 of massive mountains 443 00:15:33,673 --> 00:15:35,574 such as Everest. 444 00:15:43,783 --> 00:15:44,683 The turtleback rocks 445 00:15:44,784 --> 00:15:46,585 also offer Miller evidence 446 00:15:46,652 --> 00:15:47,953 as to when Death Valley's 447 00:15:48,054 --> 00:15:51,756 stretching started. 448 00:15:51,824 --> 00:15:53,391 Dating these rocks reveals that 449 00:15:53,459 --> 00:15:55,026 the deformation started here 450 00:15:55,094 --> 00:15:57,929 around 13 million years ago, 451 00:15:57,964 --> 00:15:59,397 although Death Valley did not 452 00:15:59,498 --> 00:16:00,932 take on its final shape 453 00:16:01,000 --> 00:16:02,500 immediately. 454 00:16:02,568 --> 00:16:04,669 >> Death Valley's really young 455 00:16:04,770 --> 00:16:06,304 when you look at the whole 456 00:16:06,372 --> 00:16:07,739 geologic time scale. 457 00:16:07,773 --> 00:16:09,474 Modern Death Valley is probably 458 00:16:09,575 --> 00:16:11,309 3 or 4 million years old 459 00:16:11,377 --> 00:16:13,545 at the most. The stretching 460 00:16:13,579 --> 00:16:15,480 started before that. 461 00:16:15,548 --> 00:16:16,748 But Death Valley itself 462 00:16:16,816 --> 00:16:20,318 is a very recent feature. 463 00:16:20,386 --> 00:16:21,686 >> Scientists know that the 464 00:16:21,754 --> 00:16:24,289 process is far from finished. 465 00:16:24,323 --> 00:16:25,657 They've found irrefutable 466 00:16:25,758 --> 00:16:27,225 evidence in the alien 467 00:16:27,293 --> 00:16:28,560 Death Valley landscape 468 00:16:28,594 --> 00:16:34,399 known as Badwater Basin. 469 00:16:34,400 --> 00:16:35,300 >> I'm standing here 470 00:16:35,368 --> 00:16:37,402 at Badwater, which is 471 00:16:37,470 --> 00:16:38,737 the lowest point 472 00:16:38,771 --> 00:16:41,673 in the western hemisphere. 473 00:16:41,674 --> 00:16:44,309 It's 282 feet below sea level. 474 00:16:44,377 --> 00:16:45,477 We're actually standing 475 00:16:45,544 --> 00:16:47,045 below sea level about the depth 476 00:16:47,113 --> 00:16:49,114 of a football field. 477 00:16:51,117 --> 00:16:52,851 This floor has been sinking. 478 00:16:52,918 --> 00:16:54,286 It's about a tenth of an inch 479 00:16:54,387 --> 00:16:56,588 per year, which is about 480 00:16:56,656 --> 00:16:57,856 half of the speed at which 481 00:16:57,923 --> 00:16:59,858 your fingernail grows. 482 00:17:02,495 --> 00:17:03,561 >> Continual stretching 483 00:17:03,663 --> 00:17:04,829 of the earth's crust 484 00:17:04,897 --> 00:17:06,131 has turned Badwater 485 00:17:06,198 --> 00:17:07,832 into one of the lowest spots 486 00:17:07,900 --> 00:17:11,303 on any continent on the planet. 487 00:17:11,370 --> 00:17:13,104 Yet its true depth 488 00:17:13,172 --> 00:17:15,273 is even lower still. 489 00:17:15,308 --> 00:17:17,008 >> The surface that we see here 490 00:17:17,043 --> 00:17:19,210 is the present-day surface. 491 00:17:19,278 --> 00:17:21,079 But what one has to realize 492 00:17:21,113 --> 00:17:22,647 is that beneath our feet, 493 00:17:22,715 --> 00:17:24,382 we can go down through sediment 494 00:17:24,483 --> 00:17:26,551 that represents ancient periods 495 00:17:26,652 --> 00:17:27,752 of time, when Death Valley 496 00:17:27,853 --> 00:17:29,354 was a surface that goes down 497 00:17:29,388 --> 00:17:32,290 3 miles. 498 00:17:32,358 --> 00:17:33,491 >> You would need to drill down 499 00:17:33,559 --> 00:17:34,459 through the sediment 500 00:17:34,560 --> 00:17:35,727 to a depth equivalent 501 00:17:35,761 --> 00:17:37,929 to 11 Empire State buildings 502 00:17:37,997 --> 00:17:39,998 end to end before you hit 503 00:17:40,032 --> 00:17:43,668 the crustal bedrock. 504 00:17:43,736 --> 00:17:45,370 The total volume of material 505 00:17:45,471 --> 00:17:46,671 in this basin would bury 506 00:17:46,739 --> 00:17:47,839 New York to the depth 507 00:17:47,940 --> 00:17:52,644 of nearly a mile. 508 00:17:52,712 --> 00:17:54,379 The valley floor is constantly 509 00:17:54,447 --> 00:17:55,747 being covered with sediment 510 00:17:55,848 --> 00:17:57,282 cascading from the surrounding 511 00:17:57,350 --> 00:17:59,751 mountains, but it can never 512 00:17:59,819 --> 00:18:03,288 fill up completely. 513 00:18:03,356 --> 00:18:04,556 >> The sediment is coming in 514 00:18:04,623 --> 00:18:06,091 at a rate that is less than 515 00:18:06,192 --> 00:18:07,292 the rate of sinking 516 00:18:07,393 --> 00:18:09,094 of Death Valley itself. 517 00:18:09,195 --> 00:18:10,528 So that we're always maintaining 518 00:18:10,563 --> 00:18:12,430 a surface here on the valley 519 00:18:12,465 --> 00:18:14,032 that is sitting below sea level 520 00:18:14,100 --> 00:18:15,367 and is continuing to sink 521 00:18:15,468 --> 00:18:17,202 through time. 522 00:18:17,303 --> 00:18:18,536 >> This constant movement 523 00:18:18,571 --> 00:18:20,839 shows Earth's geological forces 524 00:18:20,906 --> 00:18:22,907 at their most dynamic 525 00:18:22,975 --> 00:18:26,277 and makes Death Valley unique. 526 00:18:26,379 --> 00:18:28,480 >> The allure is that nowhere 527 00:18:28,547 --> 00:18:30,014 on earth do we see continental 528 00:18:30,116 --> 00:18:31,750 crusts being pulled apart 529 00:18:31,817 --> 00:18:36,554 at this rate or this magnitude. 530 00:18:36,655 --> 00:18:37,789 >> The investigation into 531 00:18:37,823 --> 00:18:39,257 Death Valley's creation 532 00:18:39,291 --> 00:18:40,992 has established how it sank 533 00:18:41,093 --> 00:18:42,427 to become the lowest point 534 00:18:42,461 --> 00:18:46,097 in North America. 535 00:18:46,198 --> 00:18:47,298 The turtleback rocks were 536 00:18:47,366 --> 00:18:48,733 deformed by the powerful 537 00:18:48,768 --> 00:18:50,268 tectonic forces pulling 538 00:18:50,369 --> 00:18:51,636 the mountains apart 539 00:18:51,737 --> 00:18:56,174 to form a wide valley floor. 540 00:18:56,242 --> 00:18:57,809 The still-sinking landscape 541 00:18:57,843 --> 00:19:00,612 of Badwater, currently 282 feet 542 00:19:00,646 --> 00:19:02,647 below sea level, is proof 543 00:19:02,715 --> 00:19:03,648 that the crust here 544 00:19:03,716 --> 00:19:09,087 is still being stretched today. 545 00:19:09,188 --> 00:19:10,889 But the sinking of Death Valley 546 00:19:10,923 --> 00:19:14,993 is just one part of the story. 547 00:19:15,094 --> 00:19:16,561 Geologists still need 548 00:19:16,629 --> 00:19:18,196 to investigate how one 549 00:19:18,264 --> 00:19:20,732 of the hottest places on earth 550 00:19:20,800 --> 00:19:22,901 was shaped by the power 551 00:19:23,002 --> 00:19:25,069 of moving ice. 552 00:19:29,787 --> 00:19:31,521 >> 1.2 billion years ago, 553 00:19:31,622 --> 00:19:33,156 Death Valley was submerged 554 00:19:33,257 --> 00:19:35,759 by ancient seas. 555 00:19:35,793 --> 00:19:37,193 Around a billion years later, 556 00:19:37,261 --> 00:19:38,795 volcanic mountains drove 557 00:19:38,863 --> 00:19:42,399 the seas away. 558 00:19:42,433 --> 00:19:43,967 13 million years ago, 559 00:19:44,035 --> 00:19:45,035 the continental crust 560 00:19:45,069 --> 00:19:47,337 started stretching apart here. 561 00:19:47,405 --> 00:19:49,606 And by 3 million years ago, 562 00:19:49,674 --> 00:19:51,041 Death Valley was one of the 563 00:19:51,075 --> 00:19:55,245 lowest points on earth. 564 00:19:55,346 --> 00:19:56,313 The clue that showed 565 00:19:56,347 --> 00:19:58,615 investigators what happened next 566 00:19:58,716 --> 00:20:00,317 was the discovery in the valley 567 00:20:00,351 --> 00:20:01,418 of a little-known 568 00:20:01,485 --> 00:20:02,986 but highly valued 569 00:20:03,054 --> 00:20:06,523 white crystalline rock. 570 00:20:06,590 --> 00:20:07,257 >> When one thinks 571 00:20:07,325 --> 00:20:08,258 of prospectors 572 00:20:08,326 --> 00:20:09,926 in the Death Valley region, 573 00:20:09,960 --> 00:20:11,328 one often thinks of them 574 00:20:11,395 --> 00:20:13,530 hunting for gold and for silver. 575 00:20:13,531 --> 00:20:14,597 But there was one mineral 576 00:20:14,699 --> 00:20:15,965 that was much less glamorous, 577 00:20:16,033 --> 00:20:17,434 much less sexy and exciting, 578 00:20:17,501 --> 00:20:19,069 and that was borax, 579 00:20:19,136 --> 00:20:20,070 but it was actually known 580 00:20:20,137 --> 00:20:22,238 as the white gold of the desert. 581 00:20:22,239 --> 00:20:24,507 >> In 1880, borax was a rare 582 00:20:24,608 --> 00:20:26,309 but in-demand mineral used 583 00:20:26,344 --> 00:20:28,712 in antiseptics and detergents. 584 00:20:28,779 --> 00:20:29,879 One impoverished couple 585 00:20:29,980 --> 00:20:30,980 desperately trying to make 586 00:20:31,048 --> 00:20:32,515 a living in Death Valley 587 00:20:32,583 --> 00:20:35,218 was Aaron and Rosie Winters. 588 00:20:35,252 --> 00:20:36,252 They heard from a passing 589 00:20:36,320 --> 00:20:37,620 prospector that they could make 590 00:20:37,688 --> 00:20:39,155 good money from borax 591 00:20:39,223 --> 00:20:41,491 if they could find it. 592 00:20:41,525 --> 00:20:42,892 They learned from their fellow 593 00:20:42,960 --> 00:20:44,794 prospector the then-secret 594 00:20:44,862 --> 00:20:46,696 method of testing rock 595 00:20:46,797 --> 00:20:48,698 for borax. 596 00:20:48,766 --> 00:20:50,066 Anxious to keep potential 597 00:20:50,134 --> 00:20:51,701 profits for themselves, 598 00:20:51,769 --> 00:20:52,869 the couple waited until 599 00:20:52,937 --> 00:20:54,070 the dead of night to perform 600 00:20:54,138 --> 00:20:57,040 the test in Death Valley. 601 00:20:57,108 --> 00:20:58,408 >> You burn the mineral 602 00:20:58,476 --> 00:21:00,043 to see if the powder 603 00:21:00,111 --> 00:21:01,378 that we have in front of us here 604 00:21:01,412 --> 00:21:04,114 contains any borax. 605 00:21:04,148 --> 00:21:05,782 Now, what the Winters did 606 00:21:05,883 --> 00:21:08,051 is to add sulfuric acid 607 00:21:08,152 --> 00:21:11,755 to borax-bearing mineral. 608 00:21:11,789 --> 00:21:13,790 We'll add some alcohol. 609 00:21:13,858 --> 00:21:15,058 The Winters probably used 610 00:21:15,159 --> 00:21:18,395 cheap whiskey back in 1880. 611 00:21:18,429 --> 00:21:20,563 And the flame should burn 612 00:21:20,598 --> 00:21:23,233 hopefully a green color 613 00:21:23,300 --> 00:21:28,238 if borax is there. 614 00:21:28,305 --> 00:21:29,105 And as we can see, 615 00:21:29,140 --> 00:21:30,940 the flame is green in color. 616 00:21:30,975 --> 00:21:33,143 And in 1880, the Winters knew 617 00:21:33,244 --> 00:21:34,310 that they would become wealthy 618 00:21:34,378 --> 00:21:36,312 because they had borax. 619 00:21:40,117 --> 00:21:41,751 >> From these humble beginnings, 620 00:21:41,819 --> 00:21:43,286 a whole industry grew 621 00:21:43,387 --> 00:21:45,722 in Death Valley. 622 00:21:45,756 --> 00:21:47,624 It made the Winters' fortune 623 00:21:47,658 --> 00:21:49,292 and also gave scientists 624 00:21:49,360 --> 00:21:50,827 a priceless clue in their quest 625 00:21:50,928 --> 00:21:52,662 to understand the geological 626 00:21:52,730 --> 00:21:57,367 history of Death Valley, 627 00:21:57,468 --> 00:21:58,802 Because borax deposits 628 00:21:58,836 --> 00:22:00,804 like these can only be found 629 00:22:00,838 --> 00:22:02,539 in the beds of ancient 630 00:22:02,573 --> 00:22:05,809 freshwater lakes. 631 00:22:05,843 --> 00:22:07,177 The sea water that once covered 632 00:22:07,278 --> 00:22:09,479 this valley had long gone 633 00:22:09,547 --> 00:22:12,715 a billion or more years earlier. 634 00:22:12,750 --> 00:22:15,351 But the presence of borax proves 635 00:22:15,386 --> 00:22:16,653 that freshwater must have 636 00:22:16,720 --> 00:22:18,354 flooded into the area 637 00:22:18,456 --> 00:22:20,023 when ice-age glaciers started 638 00:22:20,090 --> 00:22:21,357 to melt from the surrounding 639 00:22:21,459 --> 00:22:23,359 mountains around 200,000 640 00:22:23,427 --> 00:22:25,628 years ago. 641 00:22:25,729 --> 00:22:27,197 As the glaciers melted, 642 00:22:27,264 --> 00:22:28,565 rivers flowed towards 643 00:22:28,632 --> 00:22:32,101 the lowest point--Death Valley. 644 00:22:32,203 --> 00:22:34,270 Gradually a vast lake spread out 645 00:22:34,338 --> 00:22:39,008 across the flooded valley floor. 646 00:22:39,109 --> 00:22:40,543 The valley's catchment area 647 00:22:40,611 --> 00:22:43,146 was huge. Its rivers drained 648 00:22:43,180 --> 00:22:46,149 more than 9,000 square miles, 649 00:22:46,183 --> 00:22:47,550 an area bigger than 650 00:22:47,618 --> 00:22:51,120 New Hampshire. 651 00:22:51,188 --> 00:22:52,288 The water pouring in 652 00:22:52,356 --> 00:22:53,556 from the surrounding mountains 653 00:22:53,624 --> 00:22:55,692 leached minerals such as borax 654 00:22:55,726 --> 00:22:57,794 from the rocks and deposited 655 00:22:57,828 --> 00:23:01,831 them on the lake bed. 656 00:23:01,899 --> 00:23:03,900 >> In a lot of the lake beds, 657 00:23:04,001 --> 00:23:05,902 this mineral, borax, would 658 00:23:05,970 --> 00:23:07,270 appear as kind of a white 659 00:23:07,371 --> 00:23:08,438 fuzzy mineral. It was actually 660 00:23:08,539 --> 00:23:10,373 called cotton ball. 661 00:23:12,376 --> 00:23:13,776 >> the borax proved 662 00:23:13,811 --> 00:23:16,012 that a lake existed here. 663 00:23:16,080 --> 00:23:17,280 Geologists called it 664 00:23:17,348 --> 00:23:19,048 Lake Manley, after one 665 00:23:19,083 --> 00:23:20,350 of the pioneers, 666 00:23:20,451 --> 00:23:21,784 William L. Manley, who had 667 00:23:21,819 --> 00:23:26,823 named Death Valley in 1849. 668 00:23:26,891 --> 00:23:28,358 But they had no evidence 669 00:23:28,459 --> 00:23:29,726 to tell them its depth 670 00:23:29,827 --> 00:23:34,430 and its size. 671 00:23:34,465 --> 00:23:35,698 A solution to this puzzle 672 00:23:35,733 --> 00:23:37,800 is revealed in this small hill 673 00:23:37,868 --> 00:23:39,135 with a road cut straight 674 00:23:39,169 --> 00:23:40,537 through it near the valley's 675 00:23:40,638 --> 00:23:42,372 edge at a spot called 676 00:23:42,439 --> 00:23:46,509 Beatty Junction. 677 00:23:46,544 --> 00:23:48,411 >> It's very fortunate to have 678 00:23:48,445 --> 00:23:50,146 a road cut right through 679 00:23:50,180 --> 00:23:51,981 this gravel deposit. 680 00:23:52,082 --> 00:23:53,917 So, in the exposure, we can see 681 00:23:53,984 --> 00:23:56,185 very well rounded pebbles. 682 00:23:56,253 --> 00:23:57,720 We can also see some crude 683 00:23:57,821 --> 00:23:59,622 layering in the gravels. 684 00:23:59,623 --> 00:24:00,690 And they're stacked in 685 00:24:00,724 --> 00:24:02,158 against each other. 686 00:24:02,226 --> 00:24:05,428 And we call that shingling. 687 00:24:05,429 --> 00:24:06,729 >> The shape and the smoothness 688 00:24:06,797 --> 00:24:08,498 of the stones tells Caskey 689 00:24:08,532 --> 00:24:09,966 exactly how these pebbles 690 00:24:10,000 --> 00:24:13,303 got here. 691 00:24:13,404 --> 00:24:14,237 >> Yhe way they're stacked 692 00:24:14,271 --> 00:24:15,972 tells us that the direction 693 00:24:16,040 --> 00:24:18,074 of water flow that laid 694 00:24:18,175 --> 00:24:19,809 these pebbles down like this 695 00:24:19,910 --> 00:24:21,878 was from the right to the left. 696 00:24:21,979 --> 00:24:22,979 So we know that this had to be 697 00:24:23,080 --> 00:24:24,881 wave action. That's strong 698 00:24:24,982 --> 00:24:25,882 evidence that this is 699 00:24:25,950 --> 00:24:28,151 a beach environment. 700 00:24:28,185 --> 00:24:29,152 >> By looking at the height 701 00:24:29,253 --> 00:24:30,153 of this pebble beach 702 00:24:30,254 --> 00:24:31,988 above the valley floor, 703 00:24:32,056 --> 00:24:33,890 Caskey calculates the dimensions 704 00:24:33,958 --> 00:24:35,792 of the lake. 705 00:24:35,859 --> 00:24:37,126 >> From this beach gravel bar 706 00:24:37,227 --> 00:24:39,162 that we're standing on, 707 00:24:39,263 --> 00:24:39,996 the waves would have been 708 00:24:40,064 --> 00:24:41,397 crashing at our feet, 709 00:24:41,432 --> 00:24:42,966 and as we look south, 710 00:24:43,067 --> 00:24:44,067 it's hard to imagine 711 00:24:44,134 --> 00:24:45,602 a lake sitting out there 712 00:24:45,703 --> 00:24:47,236 across that vast salt pan. 713 00:24:47,338 --> 00:24:48,438 But Lake Manley would have 714 00:24:48,539 --> 00:24:50,807 covered about 600 square miles 715 00:24:50,874 --> 00:24:51,808 and it would have been about 716 00:24:51,875 --> 00:24:53,810 450 feet deep. 717 00:24:56,180 --> 00:24:58,314 It's odd mapping shorelines 718 00:24:58,349 --> 00:24:59,716 on a really hot day 719 00:24:59,783 --> 00:25:00,516 in Death Valley. 720 00:25:00,618 --> 00:25:01,417 You kind of long for 721 00:25:01,518 --> 00:25:04,253 the ancient days of yore, 722 00:25:04,321 --> 00:25:05,254 when there were big lakes 723 00:25:05,356 --> 00:25:06,255 out here. You can imagine 724 00:25:06,323 --> 00:25:08,057 this was a beautiful place 725 00:25:08,158 --> 00:25:10,927 full of lush vegetation. 726 00:25:10,961 --> 00:25:11,861 You know, it was quite 727 00:25:11,929 --> 00:25:12,495 a different place 728 00:25:12,596 --> 00:25:15,098 than it is today. 729 00:25:15,132 --> 00:25:16,666 >> For Caskey, the next step 730 00:25:16,734 --> 00:25:19,035 is discovering why Death Valley 731 00:25:19,136 --> 00:25:21,571 no longer has a lake. 732 00:25:21,639 --> 00:25:23,139 And there is evidence about that 733 00:25:23,207 --> 00:25:24,907 in one of its most unusual 734 00:25:24,942 --> 00:25:27,110 landscapes--this twisted, 735 00:25:27,177 --> 00:25:29,112 jagged field of white peaks 736 00:25:29,179 --> 00:25:29,946 that's called 737 00:25:30,047 --> 00:25:31,948 The Devil's Golf Course. 738 00:25:36,020 --> 00:25:37,387 Even the sounds here 739 00:25:37,488 --> 00:25:39,122 are mysterious. 740 00:25:39,223 --> 00:25:40,490 In the silence of the desert, 741 00:25:40,591 --> 00:25:42,492 there is a faint popping noise 742 00:25:42,559 --> 00:25:43,993 as the relentless sun 743 00:25:44,028 --> 00:25:45,928 sucks every drop of moisture 744 00:25:46,030 --> 00:25:47,864 out of the parched surface. 745 00:25:47,931 --> 00:25:51,034 [popping sounds] 746 00:25:51,101 --> 00:25:52,669 >> The salt that we see here is 747 00:25:52,736 --> 00:25:54,837 the remains of an ancient lake. 748 00:25:54,938 --> 00:25:56,172 It's called Devil's Golf Course 749 00:25:56,206 --> 00:25:57,373 because it's probably 750 00:25:57,408 --> 00:25:58,675 the least likely surface 751 00:25:58,742 --> 00:25:59,676 that you would ever want 752 00:25:59,743 --> 00:26:03,379 to play golf on. 753 00:26:03,480 --> 00:26:04,647 >> The surface is made up 754 00:26:04,748 --> 00:26:06,749 of rough salt crystals, 755 00:26:06,850 --> 00:26:08,484 popping when they expand and 756 00:26:08,585 --> 00:26:10,920 contract in the searing heat, 757 00:26:10,988 --> 00:26:13,189 but this salt did not 758 00:26:13,290 --> 00:26:15,658 come from the sea. 759 00:26:15,759 --> 00:26:17,827 Just like the borax, the salt 760 00:26:17,928 --> 00:26:19,262 was leached from the rocks 761 00:26:19,296 --> 00:26:21,197 when freshwater started flowing 762 00:26:21,265 --> 00:26:22,398 into Death Valley 763 00:26:22,466 --> 00:26:26,302 200,000 years ago. 764 00:26:26,370 --> 00:26:27,570 The salt was originally 765 00:26:27,671 --> 00:26:28,938 dissolved in the freshwater 766 00:26:29,006 --> 00:26:31,107 Lake Manley, and Caskey 767 00:26:31,208 --> 00:26:32,909 has a simple experiment to show 768 00:26:32,943 --> 00:26:34,577 exactly how it ended up 769 00:26:34,645 --> 00:26:37,914 on the floor of Death Valley. 770 00:26:37,981 --> 00:26:39,749 >> I'll pour the water and salt 771 00:26:39,817 --> 00:26:41,117 solution into this pan, 772 00:26:41,185 --> 00:26:43,086 and as the water evaporates, 773 00:26:43,120 --> 00:26:44,821 we should see salt forming. 774 00:26:44,922 --> 00:26:46,823 And that's exactly how this 775 00:26:46,890 --> 00:26:50,193 salt crust forms. 776 00:26:50,260 --> 00:26:52,729 So... 777 00:26:52,763 --> 00:26:53,930 it's hot enough out here today. 778 00:26:53,997 --> 00:26:54,997 It should evaporate 779 00:26:55,032 --> 00:26:56,999 pretty quickly. 780 00:27:00,637 --> 00:27:02,572 In a fairly short amount 781 00:27:02,639 --> 00:27:03,806 of time, there are some 782 00:27:03,841 --> 00:27:05,274 beautiful salt crystals formed 783 00:27:05,375 --> 00:27:06,809 along the edges. 784 00:27:06,844 --> 00:27:07,643 That's essentially how 785 00:27:07,711 --> 00:27:09,445 a salt pan forms. 786 00:27:09,480 --> 00:27:11,114 When the rainwater comes in, 787 00:27:11,181 --> 00:27:13,282 the salt goes into solution, 788 00:27:13,350 --> 00:27:14,550 basically just like the water 789 00:27:14,618 --> 00:27:15,718 that we have in this water 790 00:27:15,753 --> 00:27:18,988 bottle, and from the moment 791 00:27:19,022 --> 00:27:21,090 the water starts evaporating, 792 00:27:21,191 --> 00:27:25,094 salt crystals start forming. 793 00:27:25,195 --> 00:27:26,295 >> Today, Death Valley's 794 00:27:26,363 --> 00:27:27,730 salt pans cover more 795 00:27:27,831 --> 00:27:29,899 than 200 square miles, 796 00:27:29,933 --> 00:27:32,168 An area 3 times the size 797 00:27:32,202 --> 00:27:35,271 of Washington, D.C. 798 00:27:35,372 --> 00:27:36,205 They are the remnants 799 00:27:36,273 --> 00:27:37,206 of the ancient lake 800 00:27:37,274 --> 00:27:38,641 that finally disappeared 801 00:27:38,709 --> 00:27:40,643 2,000 years ago, when Earth's 802 00:27:40,711 --> 00:27:45,081 climate began to warm up. 803 00:27:45,115 --> 00:27:46,449 From then onwards, 804 00:27:46,550 --> 00:27:47,817 Death Valley's temperatures 805 00:27:47,885 --> 00:27:51,554 just kept on rising. 806 00:27:51,655 --> 00:27:52,622 >> Death Valley is definitely 807 00:27:52,656 --> 00:27:53,456 one of the hottest spots 808 00:27:53,557 --> 00:27:54,524 in the world. 809 00:27:54,525 --> 00:27:55,658 The record high 810 00:27:55,726 --> 00:27:57,927 was 134 degrees fahrenheit, 811 00:27:57,995 --> 00:28:01,264 recorded back in July 10, 1913. 812 00:28:01,265 --> 00:28:02,064 And just to give you 813 00:28:02,099 --> 00:28:03,199 perspective on that, 814 00:28:03,267 --> 00:28:04,333 the caretaker of the Furnace 815 00:28:04,368 --> 00:28:05,535 Creek Ranch, who actually 816 00:28:05,602 --> 00:28:07,203 was the one doing the recordings 817 00:28:07,271 --> 00:28:10,072 back then, he describes that day 818 00:28:10,107 --> 00:28:11,641 as being so hot, he saw 819 00:28:11,742 --> 00:28:14,076 the swallows falling dead 820 00:28:14,178 --> 00:28:17,547 in flight. 821 00:28:17,614 --> 00:28:19,382 >> Geologists today understand 822 00:28:19,449 --> 00:28:21,184 how Death Valley's unusual 823 00:28:21,251 --> 00:28:22,819 geology is responsible 824 00:28:22,886 --> 00:28:24,020 for the punishing climate 825 00:28:24,054 --> 00:28:27,323 that killed off its lake. 826 00:28:27,391 --> 00:28:29,292 It stays so dry because there 827 00:28:29,326 --> 00:28:31,160 are 3 distinct mountain ranges 828 00:28:31,228 --> 00:28:32,528 between Death Valley 829 00:28:32,596 --> 00:28:33,763 and the moisture carried 830 00:28:33,797 --> 00:28:35,431 off of the Pacific Ocean, 831 00:28:35,499 --> 00:28:38,201 over 200 miles away. 832 00:28:38,235 --> 00:28:39,435 >> We have the Sierra Nevadas 833 00:28:39,503 --> 00:28:40,570 to the west of us. 834 00:28:40,604 --> 00:28:42,038 The storms come in from the west 835 00:28:42,139 --> 00:28:43,339 laden with moisture. 836 00:28:43,407 --> 00:28:45,141 As they rise up, they lose 837 00:28:45,242 --> 00:28:46,342 most of that moisture 838 00:28:46,410 --> 00:28:47,677 on the west side, 839 00:28:47,744 --> 00:28:49,245 and each set of mountains 840 00:28:49,313 --> 00:28:50,680 wicks a little more moisture 841 00:28:50,747 --> 00:28:51,781 out of the clouds. 842 00:28:51,849 --> 00:28:53,316 And here, with our 3 sets 843 00:28:53,417 --> 00:28:55,151 of mountains in between us 844 00:28:55,219 --> 00:28:56,953 and the ocean, by the time that 845 00:28:57,020 --> 00:28:59,055 moisture gets to Death Valley, 846 00:28:59,122 --> 00:29:00,790 there's either all gone, or we 847 00:29:00,858 --> 00:29:04,126 just get a few drops of rain. 848 00:29:04,228 --> 00:29:05,761 >> Almost all storms 849 00:29:05,863 --> 00:29:07,196 from the coast are stopped 850 00:29:07,231 --> 00:29:09,232 by the 3 mountain ranges, 851 00:29:09,333 --> 00:29:10,600 each one in turn having 852 00:29:10,667 --> 00:29:12,501 an effect the scientists call 853 00:29:12,603 --> 00:29:15,504 a rain shadow. 854 00:29:15,606 --> 00:29:17,139 >> So we are in the rain shadow 855 00:29:17,241 --> 00:29:18,674 of a rain shadow 856 00:29:18,775 --> 00:29:20,509 of a rain shadow and average 857 00:29:20,577 --> 00:29:23,479 less than two inches a year. 858 00:29:23,513 --> 00:29:24,881 >> And there is another way 859 00:29:24,948 --> 00:29:26,582 that geology influences 860 00:29:26,683 --> 00:29:28,417 the desert climate. 861 00:29:28,485 --> 00:29:29,518 Air heated under 862 00:29:29,586 --> 00:29:31,420 the cloudless sky is trapped 863 00:29:31,488 --> 00:29:33,422 by the surrounding mountains. 864 00:29:33,490 --> 00:29:35,424 In summer, Death Valley becomes 865 00:29:35,492 --> 00:29:37,827 a deadly, dangerous furnace. 866 00:29:43,033 --> 00:29:44,567 The local weather station 867 00:29:44,601 --> 00:29:46,402 provides a graphic demonstration 868 00:29:46,470 --> 00:29:47,770 of how quickly that heat 869 00:29:47,871 --> 00:29:48,771 could have destroyed 870 00:29:48,839 --> 00:29:51,507 Death Valley's lake. 871 00:29:51,575 --> 00:29:53,042 Every day, Callagan checks 872 00:29:53,110 --> 00:29:55,778 the rate of evaporation. 873 00:29:55,846 --> 00:29:57,046 >> The summer months, 874 00:29:57,114 --> 00:29:58,381 it may take 5 of these 875 00:29:58,415 --> 00:30:00,149 containers here. So I'm going to 876 00:30:00,217 --> 00:30:01,784 fill them up and dump them into 877 00:30:01,852 --> 00:30:04,420 the pond until it brings the 878 00:30:04,488 --> 00:30:06,689 water level up to the needle. 879 00:30:06,757 --> 00:30:08,591 Now, our average rainfall 880 00:30:08,692 --> 00:30:10,860 is barely 2 inches a year, 881 00:30:10,961 --> 00:30:12,662 but the evaporation pond records 882 00:30:12,763 --> 00:30:17,400 up to 150 inches of evaporation. 883 00:30:17,467 --> 00:30:19,101 >> That huge discrepancy 884 00:30:19,136 --> 00:30:20,569 between the amount of rainfall 885 00:30:20,671 --> 00:30:22,505 and the speed of evaporation 886 00:30:22,572 --> 00:30:24,507 means that a lake 12 feet deep 887 00:30:24,574 --> 00:30:26,008 and 30 miles long would 888 00:30:26,043 --> 00:30:29,378 evaporate in just a single year. 889 00:30:29,413 --> 00:30:30,413 Lake Manley was bigger 890 00:30:30,480 --> 00:30:32,381 than that, but over time, 891 00:30:32,416 --> 00:30:34,383 it never stood a chance. 892 00:30:38,021 --> 00:30:39,221 The scientists' studies 893 00:30:39,323 --> 00:30:40,222 of Death Valley have 894 00:30:40,324 --> 00:30:41,390 solved the mysteries 895 00:30:41,491 --> 00:30:44,660 of its freshwater past. 896 00:30:44,761 --> 00:30:46,028 Borax, discovered here 897 00:30:46,129 --> 00:30:47,563 in the 1880s, proves 898 00:30:47,664 --> 00:30:48,998 that Death Valley was once 899 00:30:49,032 --> 00:30:52,735 filled with a freshwater lake. 900 00:30:52,769 --> 00:30:54,203 Pebbles unearthed on an ancient 901 00:30:54,271 --> 00:30:55,838 shoreline show the lake once 902 00:30:55,906 --> 00:30:58,207 covered 600 square miles, 903 00:30:58,308 --> 00:30:59,942 an area 3 times the size 904 00:31:00,010 --> 00:31:03,379 of Chicago. 905 00:31:03,480 --> 00:31:05,047 When the last freshwater pools 906 00:31:05,115 --> 00:31:07,750 dried up here 2,000 years ago, 907 00:31:07,818 --> 00:31:09,552 Death Valley started its reign 908 00:31:09,586 --> 00:31:13,289 as the driest place in the U.S., 909 00:31:13,323 --> 00:31:14,924 which makes it ironic that 910 00:31:14,992 --> 00:31:17,059 the investigation's next phase, 911 00:31:17,094 --> 00:31:18,594 examining the valley's most 912 00:31:18,628 --> 00:31:20,830 recent geological upheavals, 913 00:31:20,897 --> 00:31:22,631 involves scientists studying 914 00:31:22,699 --> 00:31:24,367 the awesome power 915 00:31:24,434 --> 00:31:26,435 of fast-flowing water. 916 00:31:31,147 --> 00:31:33,481 >> Around 100 million years ago, 917 00:31:33,583 --> 00:31:34,850 Death Valley's ancient seas 918 00:31:34,884 --> 00:31:37,752 gave way to exploding volcanoes 919 00:31:37,787 --> 00:31:38,854 whose peaks were then 920 00:31:38,955 --> 00:31:40,155 wrenched apart to create 921 00:31:40,223 --> 00:31:43,291 the lowest spot in America. 922 00:31:43,326 --> 00:31:45,493 From around 200,000 years ago, 923 00:31:45,595 --> 00:31:46,695 the valley filled 924 00:31:46,762 --> 00:31:48,663 with a freshwater lake. 925 00:31:48,698 --> 00:31:49,731 But the rain shadow 926 00:31:49,832 --> 00:31:51,066 of surrounding mountains 927 00:31:51,133 --> 00:31:56,104 dried up the water. 928 00:31:56,138 --> 00:31:57,973 For the past 2,000 years, 929 00:31:58,040 --> 00:31:59,574 Death Valley has been hotter 930 00:31:59,609 --> 00:32:01,576 and drier than anywhere else 931 00:32:01,677 --> 00:32:03,578 in North America... 932 00:32:06,282 --> 00:32:07,315 which makes it all the more 933 00:32:07,416 --> 00:32:08,750 mysterious to find 934 00:32:08,784 --> 00:32:11,219 Mosaic Canyon, a deep chasm 935 00:32:11,287 --> 00:32:13,288 seemingly cut by water, 936 00:32:13,322 --> 00:32:17,959 in this parched and arid land, 937 00:32:18,027 --> 00:32:19,561 especially when there is 938 00:32:19,595 --> 00:32:21,863 evidence of massive boulders 939 00:32:21,964 --> 00:32:23,498 having been pushed around 940 00:32:23,566 --> 00:32:27,969 like pebbles. 941 00:32:28,037 --> 00:32:29,404 >> Just look at the size 942 00:32:29,472 --> 00:32:31,373 of that boulder and look at 943 00:32:31,407 --> 00:32:34,142 how high above my feet it is. 944 00:32:34,143 --> 00:32:37,212 It's about 3 feet in diameter, 945 00:32:37,313 --> 00:32:39,147 and I can't even estimate what 946 00:32:39,215 --> 00:32:41,549 the weight of that thing is. 947 00:32:41,550 --> 00:32:43,018 >> She may be in a desert, 948 00:32:43,052 --> 00:32:44,319 but Messina knows there is 949 00:32:44,387 --> 00:32:46,054 only one force that could have 950 00:32:46,122 --> 00:32:48,924 lifted the boulder up so high. 951 00:32:48,958 --> 00:32:50,125 >> Water brought it here 952 00:32:50,226 --> 00:32:51,326 and left it here. 953 00:32:51,394 --> 00:32:53,395 The force of the water 954 00:32:53,496 --> 00:32:54,229 that came through here 955 00:32:54,297 --> 00:32:56,031 had to have been pretty severe 956 00:32:56,098 --> 00:32:57,565 in order to get that boulder 957 00:32:57,600 --> 00:32:59,034 up there plastered 958 00:32:59,101 --> 00:33:01,102 against the wall. 959 00:33:01,137 --> 00:33:02,671 This boulder gives us evidence 960 00:33:02,738 --> 00:33:04,205 about the force of the water 961 00:33:04,307 --> 00:33:06,041 that comes down these canyons 962 00:33:06,108 --> 00:33:09,277 during flash floods. 963 00:33:09,312 --> 00:33:10,578 >> A flash flood is one 964 00:33:10,646 --> 00:33:14,316 of nature's most lethal weapons. 965 00:33:14,383 --> 00:33:16,318 >> If there were a flash flood 966 00:33:16,385 --> 00:33:17,585 coming down this canyon, 967 00:33:17,687 --> 00:33:18,553 I wouldn't have enough time 968 00:33:18,587 --> 00:33:19,921 to run out of its path 969 00:33:19,956 --> 00:33:22,223 because the water flows down 970 00:33:22,291 --> 00:33:25,226 at an incredible velocity. 971 00:33:25,294 --> 00:33:26,928 Flash floods are among 972 00:33:26,996 --> 00:33:28,863 the most violent processes 973 00:33:28,931 --> 00:33:29,998 on the earth. 974 00:33:30,032 --> 00:33:32,033 They can carry material 975 00:33:32,134 --> 00:33:33,735 the size of an S.U.V. 976 00:33:33,769 --> 00:33:36,304 without any problem at all. 977 00:33:36,372 --> 00:33:37,839 >> In one of the driest places 978 00:33:37,940 --> 00:33:39,841 in the world, the floodwater 979 00:33:39,909 --> 00:33:42,477 comes from a surprising source-- 980 00:33:42,545 --> 00:33:44,479 rain. 981 00:33:49,485 --> 00:33:50,952 On average, Death Valley 982 00:33:51,020 --> 00:33:53,188 receives just two inches of rain 983 00:33:53,222 --> 00:33:58,026 a year. This is less than half 984 00:33:58,094 --> 00:34:00,095 the rain that falls on New York 985 00:34:00,129 --> 00:34:02,664 in a single month. 986 00:34:02,732 --> 00:34:04,065 But violent summer storms 987 00:34:04,100 --> 00:34:05,433 mean it can all fall 988 00:34:05,501 --> 00:34:10,505 in just a single day. 989 00:34:10,539 --> 00:34:11,873 The floods transform 990 00:34:11,907 --> 00:34:12,974 the desert landscape 991 00:34:13,009 --> 00:34:15,877 in a number of ways. 992 00:34:15,911 --> 00:34:17,445 One is known as the desert 993 00:34:17,546 --> 00:34:19,814 bloom, where seeds and plants 994 00:34:19,915 --> 00:34:21,082 that may have lain dormant 995 00:34:21,183 --> 00:34:23,351 for up to 10 years burst into 996 00:34:23,419 --> 00:34:28,256 flower after a sudden rainfall. 997 00:34:28,324 --> 00:34:29,624 This phenomenon might be 998 00:34:29,692 --> 00:34:31,226 beautiful, but there is 999 00:34:31,260 --> 00:34:32,727 another, deadlier side 1000 00:34:32,795 --> 00:34:34,229 to these floods, 1001 00:34:34,263 --> 00:34:37,532 with a human cost. 1002 00:34:37,600 --> 00:34:39,000 >> In 2004, there was 1003 00:34:39,068 --> 00:34:40,135 a flash flood that came 1004 00:34:40,169 --> 00:34:41,803 down Furnace Creek. 1005 00:34:41,871 --> 00:34:43,972 It was just this muddy slurry 1006 00:34:44,073 --> 00:34:46,541 that was dense enough 1007 00:34:46,609 --> 00:34:47,909 to pick up a vehicle 1008 00:34:47,977 --> 00:34:50,245 and carry it downhill, 1009 00:34:50,346 --> 00:34:53,248 and several people died in it. 1010 00:34:53,349 --> 00:34:56,418 The 2004 flash flood is small 1011 00:34:56,452 --> 00:34:57,419 in compason to some of 1012 00:34:57,486 --> 00:34:58,853 the events that we see preserved 1013 00:34:58,921 --> 00:35:01,389 here in the rocks. 1014 00:35:01,424 --> 00:35:02,390 >> Flash floods happen 1015 00:35:02,491 --> 00:35:04,025 all over the world, 1016 00:35:04,126 --> 00:35:05,226 but there's evidence here 1017 00:35:05,327 --> 00:35:06,961 of their particular and rare 1018 00:35:07,029 --> 00:35:08,296 geological effect 1019 00:35:08,330 --> 00:35:11,199 in Death Valley. 1020 00:35:11,233 --> 00:35:12,133 >> This marble is 1021 00:35:12,201 --> 00:35:14,102 very highly polished. 1022 00:35:14,136 --> 00:35:14,869 It's not scratched. 1023 00:35:14,937 --> 00:35:15,937 It's not gouged. 1024 00:35:16,038 --> 00:35:16,871 It's been polished 1025 00:35:16,939 --> 00:35:18,740 by very fine grained material 1026 00:35:18,774 --> 00:35:20,108 that comes down as part 1027 00:35:20,142 --> 00:35:21,943 of a flash flood. 1028 00:35:22,044 --> 00:35:23,211 So it's really smooth, 1029 00:35:23,312 --> 00:35:24,579 and it's fluted. 1030 00:35:24,680 --> 00:35:28,316 It's really unique. 1031 00:35:28,384 --> 00:35:30,118 >> To uncover how these unusual 1032 00:35:30,219 --> 00:35:32,320 polished walls were formed, 1033 00:35:32,388 --> 00:35:33,855 Messina takes a closer look 1034 00:35:33,956 --> 00:35:35,657 at what geologists term 1035 00:35:35,724 --> 00:35:37,392 the badlands. 1036 00:35:37,460 --> 00:35:38,593 >> I think it's called bad 1037 00:35:38,661 --> 00:35:41,129 because nothing will grow on it. 1038 00:35:41,197 --> 00:35:42,664 There's just this very loose 1039 00:35:42,765 --> 00:35:44,199 material out here, 1040 00:35:44,233 --> 00:35:46,634 and it erodes so readily that 1041 00:35:46,669 --> 00:35:48,470 plants can't even take root. 1042 00:35:48,504 --> 00:35:52,207 So this is "bad land." 1043 00:35:52,274 --> 00:35:53,374 >> The rock that makes up 1044 00:35:53,409 --> 00:35:54,943 the badlands is the dried-up 1045 00:35:55,044 --> 00:35:57,011 remains of the 2,000-year-old 1046 00:35:57,046 --> 00:35:59,047 lake bed that once submerged 1047 00:35:59,115 --> 00:36:01,182 Death Valley. 1048 00:36:01,217 --> 00:36:02,083 >> This is nothing more 1049 00:36:02,118 --> 00:36:03,718 than desiccated mud. 1050 00:36:03,752 --> 00:36:04,853 It's called mudstone because 1051 00:36:04,920 --> 00:36:07,388 it's slightly lithified, 1052 00:36:07,490 --> 00:36:09,390 meaning it's turned into rock. 1053 00:36:13,195 --> 00:36:14,362 >> The mudstone's minerals 1054 00:36:14,396 --> 00:36:16,197 are arranged in tightly packed, 1055 00:36:16,298 --> 00:36:19,300 flat sheets. 1056 00:36:19,401 --> 00:36:20,835 >> The rain can't penetrate 1057 00:36:20,936 --> 00:36:23,471 the mudstone, and therefore, 1058 00:36:23,572 --> 00:36:24,672 the rain picks up a lot of the 1059 00:36:24,740 --> 00:36:25,573 particles and carries 1060 00:36:25,641 --> 00:36:28,309 them downhill. 1061 00:36:28,377 --> 00:36:29,944 >> These particles are the key 1062 00:36:30,012 --> 00:36:31,479 to the canyon's smooth, 1063 00:36:31,547 --> 00:36:35,450 polished walls. 1064 00:36:35,484 --> 00:36:36,918 >> It flows through here 1065 00:36:37,019 --> 00:36:38,720 so laden with sediment 1066 00:36:38,821 --> 00:36:41,089 that it causes a lot 1067 00:36:41,123 --> 00:36:43,391 of polishing and incision. 1068 00:36:43,459 --> 00:36:44,759 So every time a flash flood 1069 00:36:44,827 --> 00:36:46,494 comes through, this canyon 1070 00:36:46,562 --> 00:36:47,896 gets deeper, the walls 1071 00:36:47,930 --> 00:36:49,397 get higher, and the rock 1072 00:36:49,465 --> 00:36:53,401 gets more polished. 1073 00:36:53,469 --> 00:36:54,836 >> The sediment-laden floods 1074 00:36:54,937 --> 00:36:56,471 can carve into Death Valley's 1075 00:36:56,539 --> 00:36:57,839 rocks with tremendous 1076 00:36:57,940 --> 00:36:59,841 speed and force. 1077 00:36:59,942 --> 00:37:01,009 These canyons have been 1078 00:37:01,076 --> 00:37:02,944 gouged out where the rocks here 1079 00:37:03,012 --> 00:37:04,012 have been fractured 1080 00:37:04,079 --> 00:37:05,747 and weakened by the continuous 1081 00:37:05,814 --> 00:37:06,981 stretching the valley 1082 00:37:07,016 --> 00:37:10,185 is undergoing. 1083 00:37:10,286 --> 00:37:11,553 >> This is up-front, 1084 00:37:11,654 --> 00:37:13,087 in-your-face geology 1085 00:37:13,122 --> 00:37:14,255 happening right here. 1086 00:37:14,256 --> 00:37:16,357 Death Valley is dynamic. 1087 00:37:16,425 --> 00:37:18,426 This is a place where things are 1088 00:37:18,527 --> 00:37:22,163 happening in a human lifespan. 1089 00:37:22,264 --> 00:37:23,598 >> In this arid desert, 1090 00:37:23,632 --> 00:37:25,333 yhe investigation has identified 1091 00:37:25,434 --> 00:37:27,168 water as the latest factor 1092 00:37:27,269 --> 00:37:28,970 in Death Valley's continuing 1093 00:37:29,038 --> 00:37:32,707 geological evolution. 1094 00:37:32,808 --> 00:37:34,442 The giant boulders plastered 1095 00:37:34,510 --> 00:37:35,877 high on the canyon walls 1096 00:37:35,978 --> 00:37:37,078 illustrate the power 1097 00:37:37,146 --> 00:37:40,448 of flash flooding in the desert. 1098 00:37:40,516 --> 00:37:42,083 The smooth walls of mosaic 1099 00:37:42,151 --> 00:37:44,152 canyon show how the dried mud 1100 00:37:44,253 --> 00:37:45,787 from an ancient lake still 1101 00:37:45,854 --> 00:37:47,255 affects how Death Valley 1102 00:37:47,356 --> 00:37:51,893 is being shaped to this day. 1103 00:37:51,961 --> 00:37:53,861 And yet some mysteries 1104 00:37:53,896 --> 00:37:56,764 remain unsolved, including one 1105 00:37:56,799 --> 00:37:58,533 of the world's most intriguing 1106 00:37:58,601 --> 00:38:01,436 geological riddles--the rocks 1107 00:38:01,537 --> 00:38:04,806 that seem to walk by themselves, 1108 00:38:04,873 --> 00:38:06,574 moving thousands of feet across 1109 00:38:06,642 --> 00:38:08,743 the floor of Death Valley. 1110 00:38:11,602 --> 00:38:13,803 >> Over 1.2 billion years, 1111 00:38:13,871 --> 00:38:14,871 Death Valley has been 1112 00:38:14,905 --> 00:38:16,305 transformed from a watery 1113 00:38:16,340 --> 00:38:18,508 landscape to a barren desert. 1114 00:38:23,847 --> 00:38:24,881 But even though geologists 1115 00:38:24,948 --> 00:38:26,716 now understand the processes 1116 00:38:26,784 --> 00:38:27,784 that have shaped this 1117 00:38:27,851 --> 00:38:29,619 extraordinary region, there are 1118 00:38:29,686 --> 00:38:34,590 still mysteries to be solved. 1119 00:38:34,625 --> 00:38:35,625 And there is no part 1120 00:38:35,692 --> 00:38:37,593 of Death Valley more mysterious 1121 00:38:37,628 --> 00:38:38,895 than an area known 1122 00:38:38,962 --> 00:38:43,699 as the Racetrack. 1123 00:38:43,801 --> 00:38:46,068 This parched, cracked lake basin 1124 00:38:46,136 --> 00:38:47,937 just 2 1/2 miles long 1125 00:38:47,971 --> 00:38:49,405 and a mile wide 1126 00:38:49,440 --> 00:38:50,506 is the setting for one 1127 00:38:50,574 --> 00:38:51,974 of Death Valley's most 1128 00:38:52,075 --> 00:38:54,610 intriguing geological puzzles-- 1129 00:38:54,711 --> 00:38:58,681 its sliding stones. 1130 00:38:58,782 --> 00:38:59,515 >> I love this place 1131 00:38:59,583 --> 00:39:00,783 because it's odd. 1132 00:39:00,784 --> 00:39:01,417 I could come here 1133 00:39:01,485 --> 00:39:02,251 a hundred more times, 1134 00:39:02,319 --> 00:39:03,319 and every time there will be 1135 00:39:03,387 --> 00:39:04,687 something different, 1136 00:39:04,755 --> 00:39:07,890 something I didn't see. 1137 00:39:07,891 --> 00:39:09,525 >> Stretching behind these rocks 1138 00:39:09,593 --> 00:39:11,394 are long grooved trails 1139 00:39:11,428 --> 00:39:12,962 in the earth. 1140 00:39:13,063 --> 00:39:14,664 It is clear that they are tracks 1141 00:39:14,698 --> 00:39:16,966 left behind as the rocks move 1142 00:39:17,034 --> 00:39:21,671 across the valley floor. 1143 00:39:21,705 --> 00:39:23,139 The puzzle is to work out 1144 00:39:23,207 --> 00:39:25,875 how the rocks can slide uphill 1145 00:39:25,943 --> 00:39:27,677 against this slightly tilted 1146 00:39:27,778 --> 00:39:29,679 surface. 1147 00:39:29,746 --> 00:39:32,682 These are no mere pebbles. 1148 00:39:32,783 --> 00:39:33,883 Some of these rocks 1149 00:39:33,951 --> 00:39:38,421 are over 700 pounds. 1150 00:39:38,489 --> 00:39:39,956 And some of the trails 1151 00:39:40,057 --> 00:39:44,026 are nearly 3,000 feet long. 1152 00:39:44,061 --> 00:39:45,228 The phenomenon was first 1153 00:39:45,329 --> 00:39:46,963 recorded here by scientists 1154 00:39:47,030 --> 00:39:49,966 some 100 years ago, and yet, 1155 00:39:50,033 --> 00:39:51,601 in this remote location, 1156 00:39:51,702 --> 00:39:53,202 no one has ever seen 1157 00:39:53,237 --> 00:39:56,339 the rocks moving. 1158 00:39:56,406 --> 00:39:57,473 Messina has been tracking 1159 00:39:57,508 --> 00:39:58,407 the movement of each 1160 00:39:58,509 --> 00:40:00,309 individual rock on the Racetrack 1161 00:40:00,377 --> 00:40:03,646 since 1996. Her gps readings 1162 00:40:03,680 --> 00:40:04,914 are accurate to within 1163 00:40:05,015 --> 00:40:07,850 a single inch. 1164 00:40:07,885 --> 00:40:10,052 >> Geology is really nothing 1165 00:40:10,153 --> 00:40:13,556 more than detective work. 1166 00:40:13,590 --> 00:40:15,791 And rather than looking 1167 00:40:15,859 --> 00:40:16,959 for evidence of things 1168 00:40:17,027 --> 00:40:19,195 that took place a long time ago, 1169 00:40:19,229 --> 00:40:20,196 what I really like about 1170 00:40:20,230 --> 00:40:21,163 working on the Racetrack 1171 00:40:21,231 --> 00:40:22,298 is you are looking at things 1172 00:40:22,332 --> 00:40:23,766 that are happening right now. 1173 00:40:23,834 --> 00:40:25,968 It's an ongoing process. 1174 00:40:26,036 --> 00:40:28,037 >> Her first clue is the surface 1175 00:40:28,105 --> 00:40:30,373 on which the rocks slide. 1176 00:40:30,407 --> 00:40:31,340 >> If I try to move my hand 1177 00:40:31,408 --> 00:40:32,508 over it, I could probably 1178 00:40:32,576 --> 00:40:34,477 file my nails right now. 1179 00:40:34,511 --> 00:40:37,213 However, after it rains, 1180 00:40:37,281 --> 00:40:38,381 there's so much clay 1181 00:40:38,415 --> 00:40:39,916 in the lake-bed sediments 1182 00:40:39,950 --> 00:40:41,851 that it gets slick. 1183 00:40:41,952 --> 00:40:44,787 It's almost like teflon. 1184 00:40:44,855 --> 00:40:45,755 You wouldn't need very much 1185 00:40:45,856 --> 00:40:47,857 force to set even a very large 1186 00:40:47,925 --> 00:40:50,293 rock into motion, just because 1187 00:40:50,394 --> 00:40:51,961 the friction on the surface 1188 00:40:52,029 --> 00:40:54,564 is almost nil. 1189 00:40:54,598 --> 00:40:56,299 >> But water alone isn't enough 1190 00:40:56,366 --> 00:41:00,670 to make these rocks move. 1191 00:41:00,771 --> 00:41:02,038 Messina has identified 1192 00:41:02,105 --> 00:41:05,575 a second factor at work. 1193 00:41:05,676 --> 00:41:06,576 >> You can have rain, 1194 00:41:06,677 --> 00:41:07,910 but if you don't have wind 1195 00:41:07,945 --> 00:41:08,811 a couple of days later, 1196 00:41:08,912 --> 00:41:09,579 I don't think these rocks 1197 00:41:09,680 --> 00:41:12,648 are going anywhere. 1198 00:41:12,683 --> 00:41:13,583 >> The Racetrack is 1199 00:41:13,684 --> 00:41:17,186 a natural wind tunnel. 1200 00:41:17,220 --> 00:41:18,654 The wind funnels into the valley 1201 00:41:18,689 --> 00:41:20,856 from the south. 1202 00:41:20,958 --> 00:41:21,991 Close to the ground, 1203 00:41:22,092 --> 00:41:23,859 the winds can exceed hurricane 1204 00:41:23,961 --> 00:41:25,761 strength, reaching speeds 1205 00:41:25,829 --> 00:41:28,197 of over 90 miles per hour, 1206 00:41:28,231 --> 00:41:29,765 enough to push the rocks 1207 00:41:29,833 --> 00:41:31,867 into action. 1208 00:41:31,935 --> 00:41:33,135 >> If you have wind 1209 00:41:33,203 --> 00:41:35,204 and there is no friction, 1210 00:41:35,305 --> 00:41:36,405 all you'd need to do 1211 00:41:36,473 --> 00:41:38,908 is hit a rock with your finger 1212 00:41:38,942 --> 00:41:40,009 like that, and it would go 1213 00:41:40,043 --> 00:41:41,677 into motion. 1214 00:41:41,745 --> 00:41:42,845 >> When all these elements 1215 00:41:42,913 --> 00:41:44,747 are in place, the rocks can 1216 00:41:44,815 --> 00:41:47,750 Begin their mysterious journey. 1217 00:41:47,818 --> 00:41:51,454 [thunder] 1218 00:41:51,488 --> 00:41:52,388 >> Since no one has ever seen 1219 00:41:52,489 --> 00:41:54,590 the rocks in motion, we can 1220 00:41:54,658 --> 00:41:57,293 only guess how fast they go. 1221 00:41:57,361 --> 00:41:58,127 But based on some of 1222 00:41:58,195 --> 00:42:00,296 the evidence that I've seen, 1223 00:42:00,364 --> 00:42:01,364 these rocks aren't 1224 00:42:01,398 --> 00:42:03,466 inching along, by any means. 1225 00:42:03,567 --> 00:42:05,267 And the best estimate we have 1226 00:42:05,302 --> 00:42:07,670 is about 3 to 4 miles an hour. 1227 00:42:07,738 --> 00:42:10,573 So a nice, brisk walk. 1228 00:42:10,641 --> 00:42:12,174 >> But until this phenomenon 1229 00:42:12,209 --> 00:42:13,809 is witnessed, the mystery 1230 00:42:13,844 --> 00:42:15,745 of Death Valley's sliding rocks 1231 00:42:15,779 --> 00:42:17,680 will remain. 1232 00:42:17,748 --> 00:42:19,115 >> I hope that this mystery 1233 00:42:19,216 --> 00:42:21,384 isn't solved. It's what 1234 00:42:21,451 --> 00:42:22,652 keeps me interested, and I think 1235 00:42:22,753 --> 00:42:23,586 it's what keeps a lot 1236 00:42:23,654 --> 00:42:25,588 of people interested. 1237 00:42:29,760 --> 00:42:30,760 >> Geologists studying 1238 00:42:30,827 --> 00:42:32,395 Death Valley have figured out 1239 00:42:32,462 --> 00:42:34,130 its extraordinary geological 1240 00:42:34,197 --> 00:42:37,933 evolution. 1241 00:42:38,001 --> 00:42:39,402 Stromatolite fossils show 1242 00:42:39,469 --> 00:42:40,836 that this area was once 1243 00:42:40,904 --> 00:42:44,206 covered by seas. 1244 00:42:44,274 --> 00:42:45,675 Turtleback rocks prove that 1245 00:42:45,742 --> 00:42:47,376 the land was stretched apart 1246 00:42:47,477 --> 00:42:49,378 by tectonic forces, 1247 00:42:49,446 --> 00:42:51,013 dropping the valley floor down 1248 00:42:51,081 --> 00:42:54,817 to the lowest point in America. 1249 00:42:54,851 --> 00:42:56,485 Pebbles at Beatty Junction 1250 00:42:56,553 --> 00:42:58,087 prove that Death Valley was once 1251 00:42:58,121 --> 00:43:00,122 covered with a freshwater lake. 1252 00:43:03,393 --> 00:43:05,461 And the smooth, polished walls 1253 00:43:05,562 --> 00:43:08,030 of Mosaic Canyon show that water 1254 00:43:08,098 --> 00:43:09,565 is still at the heart of 1255 00:43:09,666 --> 00:43:13,836 Death Valley's modern evolution. 1256 00:43:13,937 --> 00:43:15,104 Death Valley remains 1257 00:43:15,205 --> 00:43:16,639 one of the most extreme 1258 00:43:16,707 --> 00:43:19,275 geological wonders on earth, 1259 00:43:19,309 --> 00:43:21,510 and it's still evolving. 1260 00:43:21,578 --> 00:43:22,945 Its valley floor is being 1261 00:43:23,046 --> 00:43:24,580 constantly pushed apart 1262 00:43:24,648 --> 00:43:28,317 by forces deep within the earth. 1263 00:43:28,418 --> 00:43:29,919 This means that the crust here 1264 00:43:29,953 --> 00:43:31,587 will continue to stretch 1265 00:43:31,688 --> 00:43:34,190 and thin. One day, 1266 00:43:34,224 --> 00:43:35,491 tens of millions of years 1267 00:43:35,592 --> 00:43:36,859 into the future, 1268 00:43:36,927 --> 00:43:38,127 Death Valley could be 1269 00:43:38,195 --> 00:43:39,929 separated by the sea 1270 00:43:40,030 --> 00:43:44,467 from the rest of the U.S. 1271 00:43:44,501 --> 00:43:46,302 Today, Death Valley continues 1272 00:43:46,369 --> 00:43:48,204 to sink at a steady rate 1273 00:43:48,271 --> 00:43:50,473 of 1/10th of an inch a year, 1274 00:43:50,574 --> 00:43:52,308 while its surface continues 1275 00:43:52,409 --> 00:43:54,844 to be sculpted by water, 1276 00:43:54,911 --> 00:43:57,213 living proof that the Earth 1277 00:43:57,314 --> 00:43:59,215 is never at rest.