Burke Museum paleontologist Dr. Liz Nesbitt teamed up with the Port Townsend Marine Science Center to present this special feature. In these pages you’ll meet fossil marine animals and their living relatives.
The shores of western Washington are home to hundreds of different kinds of animals. Most are invertebrates—animals without backbones—such as crabs, snails, clams, and octopus. But if we are lucky, we can also see very large vertebrate animals such as whales, dolphins, and fish. The animals presented in these pages are just a fraction of the abundant and diverse marine life of western Washington. On the other hand, fossils are relatively rare in western Washington; those that have been found include a wide variety of marine vertebrates and invertebrates. Most of the marine fossils in western Washington and the Olympic Peninsula are less than 30 million years old. The oldest fossils in this region are from the San Juan Islands and date back to the late Cretaceous Period, some 80 million years ago.
Fossils record a changing climate
The Olympic Peninsula, situated between latitudes 47° N and 48° N, but exposed to currents flowing south from the northern Pacific, is bathed in cool ocean water. The sea water temperature is always around 50° F, and our marine animals are more like those that live in Alaska than those in California. Such cool, temperate conditions have persisted here for much of the last 30 million years—but it was not always this way.
Before this time, the whole world had a "greenhouse" climate: warm oceans stretched far north and south of the current tropics. Fossil crocodiles, for example, have been found in 45-million-year-old rocks in Greenland, and fossil palm trees are found in Antarctica. In western Washington, rock dating from 85 to 40 million years ago includes tropical marine fossils and a wide diversity of tropical plants, such as magnolia, banana plant relatives, and palm trees.
This change from globally warm to cool conditions can be tracked by studying the fossils found in western Washington.
Port Townsend Marine Science Center
You can see living marine animals from the shore, up close in the touchable tidepool display at the Port Townsend Marine Science Center. The fossils are housed in the Paleontology collections of the Burke Museum in Seattle. Some of the best specimens are on display in the museum gallery and at the PTMSC Natural History Building.
Dynamic geology sets the stage
The rocks that make up the Olympic Peninsula and its surrounding shores are all composed of sediments that were deposited under the sea. Sand and silt accumulated on the ocean floor and became layers of hard rock thousands of meters thick. Occasionally animals that were buried in the sediment became fossils.
About 10 million years ago, the Olympic Mountains began to rise, rapidly pushing this rock above sea level and exposing the fossils. These huge tectonic forces resulted in many folds and faults in the sedimentary rocks that make up these beautiful mountains. Ice, snow, rain, wind, and some substantial earthquakes have carved the mountains, Puget Sound, and all the bays and inlets of our shores, providing perfect homes to a myriad of animals beneath and above sea level.