The US State of Alaska is located in the furthest most north-westerly part of North America. This is a dynamic wilderness landscape of geological and environmental contrasts rich in fossils and shaped by uplift, intrusion, earthquakes, volcanism, glaciation and sea level change.
The territory of Alaska was admitted to the union as the 49th state in January 1959 some 92 years after Russia sold the territory to the United States for the sum of US$7.2 million dollars in the Treaty of Cession.
The Treaty of Cession with Russia was negotiated and signed by the Secretary of State William Seward and Baron Edouard de Stoeckl the Russian Minister to the United States on behalf of Emperor Alexander II.
At the time the purchase was viewed negatively with some calling it, "Seward's Folly" or "Seward's Icebox", but this thinking dramatically changed when in 1896 a First Nation Tagish resident of the Dak l'a Weidi Clan called Keish (aka Skookum Jim, James Mason) and his family discovered gold.
They found a gold deposit along the Rabbit (Bonanza) Creek near the Klondike River in Canada's Yukon Territory sparking one of the largest gold rushes in history.
The fossil record of Alaska starts as far back as the Palaeozoic Era dated between 541 – 251.9 million years ago. In North America, the Palaeozoic Era is generally characterised by periodic advances and retreats of shallow seas and repeated continental tectonic activity that formed the Appalachian Mountains during the Alleghenian orogeny or mountain-building event.
The oldest known fossils of Alaska include algal mats of stromatolites (meaning “stony carpets”) of giant lithified, microbially produced, domes as well as trilobites, echinoderms and brachiopods.
Up and until the end of the Cretaceous Period dinosaurs lived in parts of Alaska. The key dinosaur sites of Alaska include the Western North Slope, Colville River, Yukon River, Denali National Park & Preserve, Talkeetna Mountains, Wrangell St. Elias National Park & Preserve, Aniakchak National Monument & Preserve and Black Lake.
Above is a a three toed dinosaur track in relief from the grey rock of the Lower Cantwell Formation dated between 65 - 80 million years ago for the Denali National Park & Preserve, Alaska.
The map below shows these locations and the terrane accretion or blocks of continental fragments and oceanic islands that have collided and permanently attached Alaska onto the rest of North America over the past 200 million years.
These include the areas of continental collision during the Laramide Orogeny between 80 - 35 million years ago that formed the Brooks Range in the northern part of the state following the subduction of Farallon and Kula oceanic plates beneath the west coast of North America. The North Slope formed as the colliding continent pulled away and opened the Arctic Ocean.
The sediments of the North Slope that form the fossil rich Prince Creek Formation are dated from the Upper Cretaceous spanning the Campanian-Maastrichtian stages. Today the steep banks of the Colville River on Alaska’s North Slope above today’s Arctic Circle has exposed many dinosaur fossils.
Among the dinosaurs discovered on the North Slope have been the carnivorous Saurischia (meaning “lizard hipped”) theropods dating back 69 million years ago. These dinosaurs were bipedal and walked on their hind legs. Among the dinosaurs include Nanuqsaurus hoglundi as smaller relative to the Tyrannosaurus rex; a Troodon, and a smaller more agile Dromaeosaridae and ostrich-like Ornithomimids.
Of the Ornithischia (“bird hipped”) plant eating dinosaurs the fossil record shows both crested and non-crested Hadrosaurids or duck-billed dinosaurs. Small bodied bipedal Hypsilophodontids, large bodied Ceratopsids and dome headed Pachycephalosaurids.
Along with the Alaskan state mineral of gold and the state rock of jade the woolly mammoth (Mammuthus primigenius) was adopted by the State of Alaska in 1986. These megafaunas lived alongside the steppe bison (Bison priscus), the Giant Beaver (Castroroides ohioensis) – the largest rodent of all time, the horse (Equus sp.) and also the mastodon.
These animals would have roamed in herds or larger extended family groups across northern Alaska up and until approximately 10 - 12,000 years ago. It is believed that the last population of woolly mammoths on Earth lived on Wrangel Island, a remote island in the Arctic Ocean. They were cut off from the mainland by rising sea levels and died out 4,000 years ago until environmental factor and extreme climate change compounded to lead to their declining health and eventual demise.
There were also a number of extant or species that are still alive today on the mainland such as the caribou, muskox, and brown bear that also lived alongside these extinct megafaunas.
The mammoth tooth shown above was discovered in a lake in Bering Land Bridge National Preserve by National Park Service aquatic ecologist Amy Larsen and pilot Eric Sieh. This mammoth tooth was radiometrically dated using carbon-14 isotopes, producing an age of 12,330 radiocarbon years before present.
A semi-articulated mammoth humerus and ulna, two mammoth vertebra, a mammoth rib fragment, and possible mammoth cranial bones were discovered in proximity to the tooth. Because these bones were found clustered together, they likely originated from a single individual. Finds of multiple mammoth bones from the same skeleton are relatively uncommon in Alaska, making this one of the more complete mammoth skeletons known from the state.
The woolly mammoth is believed to have travelled between the continents of Asia and North America via the Bering land bridge an ancient crossroad known as Beringia. During the Pleistocene Epoch dated between 2.588 million – 11.8 thousand years ago periodic ice ages and interglacial periods opened up and submerged this intercontinental causeway.
The woolly mammoth were large elephant-like mammals well-adapted to cold environments, with a thick layer of fur and long, curved tusks that they used to scrape snow and ice off of vegetation.
A distant relative, in the order Proboscidea, to the woolly mammoth was the mastodon (Mammut americanum). They shared similar features in being large, hairy, having trunks and had a plant eating diets.
Mastodons were more common in forests and wetlands, while woolly mammoths were better adapted to the cold, open grasslands of the northern latitudes. The mastodon had a distinctive set of upward-curving tusks, which they likely used to strip bark from trees and to defend themselves against predators. Mastodons also had a pair of shorter tusks or "incisors" in their lower jaw, which they used to help them gather food.
The glaciers of the ice age would freeze and lock up the water and sea levels dropped. This created a large area of fertile tundra grassland rich in grasses, mosses and lichen that supported plant eating woolly mammoths. Over time plants and animal migrated between the two continents. During the interglacial periods the glacier melted and the sea level rose.
Today the only land that remains visible along the Bering Straits are the Diomede Islands, the Pribilof Islands of St. Paul and St George, and St. Lawrence and King Island. In 1978 this area became a National Monument known as the Bering Land Bridge National Preserve managed by the US National Parks Service.
Museums to Visit
Museum of the North (Visit Website)
Alaska Museum of Science and Nature (Visit Website)