The Carboniferous in Washington, US

Paleontology and geology

Although not identified on this map, Carboniferous marine rocks in the North Cascades terrane (east of Puget Sound) include small outcrops that apparently bear no relationship to each other. These limestones and shales contain a variety of both reef-building and non-reef-building fossil invertebrates such as corals, bryozoans, brachiopods, trilobites, ammonites, clams, and snails, indicating that they formed in warm, shallow seas far to the south of their present location. Tectonic activities later moved these blocks northward and plastered them to the western edge of North America.