Washington boasts fossils as much as 550 million years old, from imprinted palms and seashells in sandstone bluffs in the northwest part of the state to the remains of a temperate forest in the northeast. The state's Department of Natural Resources offers geologic maps and fossil reports -- and permits -- to help hunters seek out likely fossil locations. At several sites in the state, though, fossils are easy to find.
Near the city of Republic, in the Okanogan highlands of northeast Washington, lies the preserved remains of a temperate forest that existed 50 million years ago. Part of the area is under a lake bed, and the sediment and volcanic ash that settled there trapped plants, insects and fish, and created one of the state's most renowned homes for fossils. Amateur paleontologists can get an inexpensive day permit and rent tools at the Stonerose Interpretive Center.
On State Route 11, also known as Chuckanut Drive, sandstone bluffs are visible about 10 miles south of Bellingham in northwest Washington. During the Eocene epoch 55 million years ago, the area was a vast, warm floodplain, and trapped in its ancient sediments were palm and horsetail leaves, parts of Sequoia trees, ferns and more. The fragile bluffs can break apart easily, making the road prone to rock slides that have the unintended benefit of exposing the imprints and petrified remains of those plants.
Layers of lava covered the Columbia Plateau in central Washington 10 to 15 million years ago. Two million years ago, one of the world's largest floods scoured the land, leaving layers of those flows -- and the fossils they contained. One of the state's most famous fossils was found there, a few miles south of Dry Falls, in an area called Blue Lake, writes David B. Williams in a May 2010 post on HistoryLink.org. In 1935, a group hiking near there found a mold and several bones of a small rhinoceros, which was later dubbed the "Blue Lake Rhino."
Heading toward the westernmost tip of Washington is the Clallam Formation, an exposure of 20-million-year-old sandstone and siltstone outcrops running 50 miles from Cape Flattery to the west and Freshwater Bay to the east in Clallam County. The area is rich in fossils from the Miocene and Oligocene ages, a span of 5 million to 30 million years ago. The Burke Museum of Natural History and Culture's collection of marine fossils includes preserved geoduck and other clams, scallops and crab found in Clallam. Fossilized whale bones also have been reported.