Rocky Mountain

Colorado's Rocky Mountains' upward pitch sires a multiplicity of ecosystems. Lowland aspen surrender to alpine evergreens that shrivel into snarled bonsai that evaporate at the tree line into tundra prairie, where flowers tower as the highest flora.

Over 560 km of trails lattice the 100-sq-km park.

Altitudes that peak at 4.3 km leave hikers gasping－both in awe and for scant oxygen.

Trail Ridge Road is the country's highest paved motorway, while the mostly gravel Old Fall River Road follows old Indian hunting routes.

The array of elevations conjures diverse wildlife, with over 60 mammals and 280 avian species. Mountain lions tackle bighorn sheep, while bobcats pounce upon smaller prey. Elk herds can swell to populations of 600.

Yosemite

Celebrated naturalist John Muir declared of Yosemite: "It is by far the grandest of all the special temples of nature I was ever permitted to enter."

Its divine topography is sculpted by tectonic activity that crunched plates together in slow motion and gushed with volcanoes before it was ground by glaciers－some of which survive, although as ghosts of their former selves.

Such landscapes produce plentiful waterfalls, including the continent's highest at 740 meters, and granite domes. El Capitan's 1-km face is one of world's most celebrated rock-climbing destinations. Camp 4 is credited as a birthplace of the sport.

Over 1,300 km of trails trace elevations that swoop from 650-4,000 meters, generating five vegetation zones in this swathe of California's High Sierra hosts. The terrain bristles with 92,000 hectares of old-growth forests, including three giant sequoia groves.

Yellowstone

Grizzlies, bison and wolves rove among the world's greatest concentration of geysers, including Old Faithful. The 300 spouts stand out among Yellowstone's 10,000 thermal formations, including mudpots, hot springs and fumaroles.

The park that spans hunks of Wyoming, Montana and Idaho also hosts the planet's biggest petrified forest and its largest calderas.

Its geological idiosyncrasies inspired the preservation of its ecology as the country's first national park.

It's inhabited by seven ungulates, including bison, moose and pronghorn, and nearly 70 other mammals, 320 bird species and 16 types of fish. They dwell among over 1,100 native plant species.

They're the life force of this otherworld on Earth－one from ancient days before modern mankind so manicured and domesticated our planet that we rendered it unrecognizable compared to its natural and wild self.