Paleontology and geologyDuring the Quaternary (Pleistocene), glaciers carved the landscape of northernmost Washington and the Puget Sound region in the western part of the state. Sediments left behind by the melting ice can be seen in these areas. Large lakes formed by glacial meltwater burst their natural dams, causing huge floods that scoured out the Columbia River gorge and other major river channels in the state. Volcanoes continued to erupt, building the familiar volcanic cones of the Cascade Range. Larger mammals are represented in Pleistocene deposits by mammoth and mastodon teeth and tusks, as well as the bones of giant sloths. |
