Geology & Fossils
Are you kidding? How can you describe the prehistoric heritage of a state as big as Alaska?
Depending on what part of Alaska you visit, you can find fossils of marine invertebrates from the distant Paleozoic Era, Dinosaurs from the Cretaceous Period, or Ice Age mammals that disappeared just yesterday (in relative terms).
Much of Alaska us underlain by permafrost. This is soil that is frozen year round. Therefore, it is not easy digging up fossils in Alaska. And fossils in tundra areas are generally covered with vegetation and muck.
But fossils are found lying on the surface here and there in upland areas and along coasts. Fossils of marine invertebrates, such as clams and snails, can be found on mountains north of the Arctic Circle, for example. Similar fossils are found in island cliffs in south-central Alaska.
Alaskan Dinosaurs
Some bones discovered along the Colville River, near the Arctic Ocean, in 1961 proved to be especially interesting. They were the first dinosaur bones found above the Arctic Circle!
The most abundant fossils were of a hadrosaur, or duckbilled dinosaur. Remains of four other dinosaur species have been discovered, including a horned dinosaur and an animal related to Tyrannosaurus. The animals lived 66 to 70 million years ago, near the end of the Cretaceous Period. Scientists aren’t sure whether these polar dinosaurs were year-round residents or simply migrated, similar to the many birds which still travel to Alaska to nest.
The Ice Age
Although the news about the discovery of dinosaurs on Alaska’s North Slope made headlines, the Ice Age is what makes Alaska really sizzle. It isn’t just the freshness of its fossils (including mammoth remains with hair and flesh).
Alaska is special because of its geographic position as North America’s closest point to Asia. During the Pleistocene Epoch (“Ice Age”), much of Earth’s water was stored in great continental glaciers. This caused sea level to fall dramatically, exposing dry land between Alaska and Asia, thus linking the New World (North and South America) with the Old World (Eurasia and Africa).
Although it’s often described as a “land bridge,” this area of new land actually covered a vast area which scientists call Beringia. Beringia was a northern wildlife refuge that remained uncovered by the continental glaciers that covered so much of the northern continents.
You may know that “steppe” is a word used to describe the vast grasslands of Central Asia. It’s pretty similar to North America’s Great Plains. “Mammoth steppe” is the name scientists gave to the grasslands of Ice Age Alaska.
Many species of plants and animals crossed over the Bering “land bridge.” Porcupines evolved in South America, horses in North America. Porcupines spread into North America when those two continents were united. From North America, horses and porcupines crossed the Bering Land Bridge and spread across Eurasia and Africa.
Horses later became extinct in North Amertica, for reasons no one knows. Many thousands of years later, European explorers brought horses back to North America. Thus, horses wouldn’t exist if not for the Bering Land Bridge!
Old World animals that crossed the Bering Land Bridge into North America include lions, cheetahs and muskoxen. The most important immigrants were humans, who entered North America more than 10,000 years ago.
Remains of woolly mammoths, long-horned bison, horses, and other Ice Age creatures are commonly found when people excavate buildings or roads. Gold miners sometimes use powerful hydraulic hoses to blast through permafrost in their search for riches. Such operations uncover countless fossils.
Other fossils are found along rivers and streams. Fossils found on river beds or lying on the banks are generally broken and scattered. But locations where rivers erode cliffs in which fossils are buried may yield complete animals.
Blue Babe
Alaska’s best-preserved Ice Age fossil isn’t a mammoth but a long-horned bison, Bison pricus. It was discovered near Fairbanks in 1979. A gold-miner was blasting through soil with a powerful hose when he saw legs with hooves, hide, and flesh! A mineral called vivianite gave the skin a bluish appearance, and the animal came to be known as Blue Babe.
The Ice Age mummy was examined by a paleontologist. He estimated that it lived about 35,000 years ago. It was an old male that died in winter, as suggested by its winter underfur. Winter is a hard time when many animals die of starvation. Part of the bison had been eaten.
The paleontologist was surprised to discover plentiful fat under the animal’s skin. Blue Babe hadn’t starved!
He studied scratch marks on the bison. They were similar to wounds African lions leave when killing buffalo. Had Blue Babe been killed by a pair of lions during an Ice Age winter?
A chip from a tooth was found under the skin. It was from a lion! The animal had probably tried to eat some more after Blue Babe froze and broke its tooth.
Cave paintings from Europe indicate that Ice Age lions had short manes or no mane at all and hunted alone or in pairs. Even today, lions that live in harsh habitats, like deserts, are short-maned and may hunt alone.
Blue Babe was likely killed by two short-maned lions, who fed on it for several days. Other animals may have fed on the carcass through the winter. In spring, a river buried it under sediments and it was preserved for 350 centuries.
Fossils in Our Lives
Alaska may have half of all the coal in the United States. But it is far better known for its vast oil deposits, most of which rest beneath the North Slope, along the Arctic Ocean. In one of the greatest engineering feats the world has ever seen, an enormous pipeline was laid across Alaska, fromPrudhoe Bay, on the Arctic coast, south to the Gulf of Alaska port of Valdez.
Today, the remains of sea creatures that lived many millions of years ago flow through the Alaska pipeline. Most of this oil winds up in automobiles or is used to heat homes across the United States. In one disastrous shipwreck (the Exxon Valdez), some of the oil was returned to the sea from whence it came.
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