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The Rocky Mountains.

A giant mountain range rising over North America.

A nearly 5,000 kilometer long chain of rugged peaks and rolling hills between British Columbia and New Mexico.

The Rocky Mountains form the easternmost part of an even greater continental mountain system, the North American Cordillera.

From foothills to alpine tundra, the slopes are covered by dense foliage.

Aspen and cottonwood are only guests here.

Ponderosa pine, Lodge pole pine, Douglas fir and Engelman spruce make the greater part of the forest.

For centuries, the Rockies stood as an impassable barrier between the Midwest and the Pacific Coast of America.

Only a few took on the challenge to cross this infatuating landscape on the steep, perilous trails.

Many of those who did never made it to the other end.

Today, the crossing of the mountain range is no longer a race against time and dwindling supplies.

And yet, despite the many visitors, parts of the landscape seem undisturbed.

The Rocky Mountain National Park is one of these protected areas.

Towering above the prairies, this epic landscape embodies our ideals of the wildness and freedom of America.

What was once a limit to the country's expansion is today a national treasure.

The Rocky Mountain National Park is far more than a hiker's paradise or magnet for photographers.

It also supports a complex ecosystem of vast forests, alpine meadows and the wildlife that inhabits them.

And to those who can read history from the icy peaks, these rugged giants reveal a crucial chapter of America's genesis.

A chapter that spans almost two billion years.

Botanists are park regulars too. At least ten different tree species cling to every square inch where they can strike root in the rocky soil.

Even so, one fourth of the park's terrain lies above 11,500 feet, the limit beyond which trees are unable to grow.

Following the Fall River toward the foothills of western mountains, one experiences a much milder side of the Rocky Mountains.

A marshland with a river meandering through it.

From a vantage point, we are treated to a breathtaking view of this marshland of the Fall River, Horseshoe Park.

Once free of snow, Horseshoe Park attracts large groups of American elk.

These iconic mammals have roamed these valleys in great numbers for millennia, but once settlers had arrived, they started to massively hunt elk in these forests and marshlands.

When the National Park was established in 1915, the elk stood on the brink of extinction. It took unremitting efforts to save them.

Today, their population in the park numbers 800 individuals.

Today, newborn and first-year calves can graze peacefully among the ponderosa pines and aspens.

The slightly drier climate of the eastern side of the National Park are ideal for ponderosa pines.

Rooted in the rocky soil, their cinnamon-red trunks can grow up to 40 meters high.

It's May in the Rockies. Though fast-building clouds can bring snow until as late as July, the white carpet is gradually receding from the slopes.

The thaw sends fast creeks down to the valley. The Fall River carries their fresh water to the Big Thompson River.

Then, the water travels all the way to the Mississippi River and the Gulf of Mexico.

The U-shaped valley of Horseshoe Park is the product of massive glaciers.

During the latest ice age, a 500-foot-thick glacier flew along the valley and widened it further.

15,000 years ago, the glacier started to melt and left its heavy load of rock and sediment behind.

Its water gave birth to the Fall River and the Kettle Ponds around, whereas the sediment became the soil of the meadows.

North of Horseshoe Park rises the famous Mummy Range with 12 peaks over 10,000 feet.

The ragged peak of the Mummy Mountains is not the highest in the range which was named after it, but it is one of the most photographed.

Hags Peak and Fairchild Mountain connect Mummy Mountain with another signature summit of the range, Ypsilon Mountain.

Its jagged peak looms above 13,500 feet.

Crossing the park in an east-west direction, the famous Trail Ridge Road winds up on the mountains to reach an altitude of almost 12,000 feet.

This iconic road offers sweeping panoramic views and the dizzying specter of the deep valleys.

The slopes of Tombstone Ridge and the surrounding peaks stay snow-clad until as late as July. The Rockies have some patches of snow all year round.

Overlooking the stunning Horseshoe Park, we can see the Fall River snaking through the glacier-scoured valley.

The shallow, sheep lakes that speckle the valley are but a few of the park's 150 ponds.

From the marshlands to the Alpine Tundra, the Rocky Mountains support four different ecosystems.

The slopes between the flat meadows and the barren peaks are ruled by dense, almost endless woodlands.

As we climb uphill, the terrain becomes harsher for the trees. The unrelenting winters put to the test every spruce, fir, and pine tree that cling to the slim soil.

At about 11,000 feet, the vegetation becomes puny. This is the zone of the Alpine Tundra.

The importance of this landscape goes well beyond the park's boundaries. These snow caps influence the lives of millions in the southwest.

For meltwater of the mountains feeds one of America's most important rivers. The Colorado River takes its source in the park.

Standing at its headwaters, one can hardly believe that further downstream, this river becomes so powerful that it has carved out the Grand Canyon.

This marshy, lush meadow with stray patches of forest expands in the famous Kawaneach Valley.

On its western side, the valley is flanked by the Never Summer Mountains, a small but high-rising range.

The new green shoots of grass and the fresh, clean water of the Colorado River draw herds of American elk to the valley.

The Pacific Drainage Area starts right here. The Rocky Mountain National Park straddles the Continental Divide, which separates the Atlantic and the Pacific drainage systems. Every drop of water on this side of the park flows into the Pacific Ocean.

Spring and summer months see creeks roaring down in their narrow gorges.

Thanks to abundant snowfall, the Rocky Mountains send huge amounts of fresh water down the Colorado and Mississippi drainages.

All in all, 450 miles of streams run across the Rocky Mountain National Park.

But climate change is shortening the winters in the Rockies, and the Mountain snowpack is decreasing.

The receding of glaciers and the thinning of snowcaps means that some of the creeks could eventually dry up. All of this might change the delicate age-old ecosystem of the Rockies.

The forests of the Montaigne and the subalpine zones of the park are in for drier summers, more frequent wildfires, and the spread of non-native species. The subalpine zone could shift up in altitude and shrink.

Scientists are expecting soil chemistry to change, and the future plants will have to strike root in a drier, more rugged ground.

The park will need to adapt to a new timetable of snowmelt, greening up and deep freeze.

On the eastern side, at 9,450 feet, the winter takes its time to yield to spring. Beyond a solid sheet of ice lies one of the most famous glacier lakes of the park, Bear Lake.

The top of the Rocky Mountain National Park, the 14,259 foot high Longs Peak, is among the 50 summits above 14,000 feet in Colorado.

By August, even Hallet Peak will have lost its white blanket.

But at this altitude, winter is never completely gone. Though the mountains have distinct seasons, it can snow any month in the Rockies.

These roots are built to cope, but they look more like claws, muscles, flecks to hold these limber pines to the loose ground.

These mountaintops are changing monuments to growth and destruction, two amazing conflicting dynamics that clash in the arena of time.

The life and decay of a tree or forest is but a split second in this endless battle.

The oldest building blocks of the Rocky Mountains were created up to 1.8 billion years ago, yet the mountains themselves, with their age of about 70 million years, count as newcomers.

Between 1.8 billion and 100 million years ago, long before the Rockies were born, this part of the continent had seen previous mountain systems rise and being eroded, one after the other.

The eroded terrain was submerged by shallow seas during the era of the dinosaurs.

Erosion has been at work ever since. Snow and wind sculpted spiking peaks. Streams cut V-shaped valleys into the rock. Giant glaciers deepened the river valleys. The massive ice flows left U-shaped valleys and scores of glacier lakes in their path.

Later, as the North American plate met the Pacific plate, the giant forces thrusted the area upwards again, up above 12 to 14,000 feet.

Today, the park is home to a variety of large mammals, like the bighorn sheep, the signature animal of America's high mountains, and the American elk.

The park's meadows, hiking trails, and scenic overlooks draw hundreds of thousands of visitors every year. But no matter how many fellow travelers hit the trails, one feels truly alone with nature among the peaks.

The greatest natural wonders change people forever.

In the Rocky Mountain National Park, we get to breathe crisp, thin air on the summits,

dip our toes in crystal clear creeks, and meet rare wildlife.

In the Rockies, we live the freedom of the first Americans, and the wilderness of our planet.