Paleontology and geology
Although not identified on this map, marine and continental Devonian sediments are found as thin slivers of rocks that began their existence far to the south and west of their current location. These slivers were caught up within exotic terranes located east of Puget Sound. Tectonic processes eventually shoved these blocks of crust up against the western edge of North America at various times after the Devonian. Washington’s Devonian rocks include plant fossils and a variety of marine fossils such as crinoids, corals, brachiopods, and foraminifera.