Gates of the Arctic National Park & Preserve


Gates of the Arctic National Park
Gates of the Arctic National Park

At 8,472,506 acres, Gates of the Arctic National Park is the second largest national park in the United States. The entire park is north of the Arctic Circle. President Jimmy Carter signed the paperwork on December 1, 1978 that designated this area as a National Monument. National Park status was automatic as soon as the 1980 Alaska National Interest Lands Conservation Act was signed. A large part of the property is preserved as Gates of the Arctic Wilderness. The area supposedly got its name during an expedition with wilderness activist Bob Marshall. He was exploring the upper reaches of the North Fork of the Kobukuk River when he came to Frigid Crags and Boreal Mountain. The two mountains stand silent sentry on both sides of the river, so he gave this the name "Gates of the Arctic" and the moniker has stuck.

The park mostly contains landscape of the Brooks Range: high, sharp, glaciated peaks that drop to glacier-carved valleys. The snowmelt feeds into the tributaries of several rivers, six of which (John River, Alatna River, Koyukuk River, Kobuk River, Tinayguk River and the Noatak River) are designated National Wild & Scenic Rivers.

Geologically speaking, much of the landscape rises above a crystalline basement into a band of partially metamorphized PreCambrian and Paleozoic sedimentary layers. Above that is a band of middle Cambrian sediments, then the Kanayuk Conglomerate: a river delta deposit up to 30 miles wide, 500 miles long and 8,000 feet deep. The Kanayuk Conglomerate was deposited during the Devonian era and continued into the early Carboniferous era. The landscape we see today has been heavily carved by glaciers since before the last Ice Ages.

The upland regions of Gates of the Arctic are primarily tundra and exposed rock. Conifers and shrubs begin to appear down in the valleys but once the valleys exit the mountains tundra takes over again. In this countryside you might come across caribou, moose, barren-ground grizzly bear, black bear, Dall sheep, arctic and gray wolf, red fox, wolverine, beaver, river otter, muskrat, marmot, pine marten and mink.

There are no roads that access the park. No trails, no campgrounds, no visitor facilities of any sort. There are 10 small villages, about 1,500 people in all, who live inside the boundaries of the park, in a special "resident subsidence zone." The Dalton Highway passes by about 5 miles east of the eastern boundary and the National Park Service participates in an interagency visitor center at Coldfoot on the Dalton.

Gates of the Arctic National Park is about four times the size of Yellowstone National Park and sees significantly fewer visitors...

The Arrigetch Peaks in Gates of the Arctic National Park
The Arrigetch Peaks in Gates of the Arctic National Park & Preserve
Map of Gates of the Arctic National Park
Gates of the Arctic National Park map
Click or tap on the map to see a larger version

Geologic Time Scale

The K-T Boundary near Trinidad, Colorado
The K-T Boundary is that white band beneath the upper layer of sandstone
Subdivisions based on Strata/Age Radiometric Dates (millions of years ago)
Neogene 0-2
Paleogene 2-65
Laramide Orogeny 63-65
Cretaceous-Tertiary Extinction Event 65
Cretaceous 65-145
Jurassic 145-210
Triassic 210-255
Permian-Triassic extinction event 251-260
Permian 255-280
Alleghenian Orogeny 260-325
Carboniferous: 280-360
-Pennsylvanian 280-320
-Mississippian 320-360
Devonian 360-415
Silurian 415-465
Ordovician 465-520
Cambrian 520-540
Precambrian Eons 541-4600
-Proterozoic 541-2,500
-Archean 2,500-4,000
-Hadean 4,000-4,600

The table to the right gives a rough breakdown of the geological ages of Earth as used in modern Geology texts.

Much of the oil and gas we use comes from vegetative deposits made during the Permian and Pennsylvanian (late Carboniferous) ages. A lot of the coal we use (with its accompanying methane gas) comes from the great jungles and forests of the Mississippian and Pennsylvanian (early and late Carboniferous) ages in the Paleozoic era. Big reptiles and dinosaurs lived out their lives during the Triassic, Jurassic and Cretaceous Periods of the Mesozoic Era.

It was at the end of the Cretaceous Age that the Laramide Orogeny was set in motion, the Colorado Plateau uplifted and the Ancestral Rocky Mountains built. That was also during the time when an asteroid impacted near the Yucatan Peninsula and tipped the environmental scale in a direction that wiped virtually all the dinosaurs from the face of the planet. The K-T Boundary is a thin layer of iridium that filled the atmosphere during that explosion, then fell back to Earth during the global fires and the atmospheric upheaval afterward. While there have been plenty of marine, insect, reptile, amphibian, plant and mammal fossils found from times since, there has never been a dinosaur fossil found from the years after that impact. The K-T boundary is accepted as the definitive marker between the Cretaceous and Tertiary Ages, the marker of the Jurassic extinction event.

The Permian-Triassic extinction event seems to have happened in two major pulses about 9 million years apart. During the Permian age many insect orders had grown huge. A rise in CO2 in the atmosphere led to a rise in temperature and to acidification of the oceans. Marine invertebrates with carbon-based skeletons suffered worst but this was also the only mass extinction that affected insects: eight or nine insect orders became extinct and ten more suffered greatly reduced diversity. Insects, however, had generally recovered by the late Triassic, everything but that giant size anyway. The second pulse seems to have occurred around the time of the Araguainha impact, an asteroidal impact in Brazil that was not large enough to set off catastrophic extinction by itself but it occurred in an area filled with oil shale and the resulting sudden rise in global warming from the fires that ignited may have begun the atmospheric cascade that led to ocean surface temperatures around 104°F (40°C). That high an ocean temperature meant it was too hot for many marine species to survive. When it was over, more than 70% of terrestrial species and almost 90% of marine species had died out. Some land ecosystems took 30 million years to recover.

Photo of the K-T Boundary courtesy of TheArmchairExplorer, CCA-by-SA 4.0 License