Western U. S. Terrane Accretion

The yellow and green shows material added (accreted) to the western edge of North America during the past 200 million years. The North American Craton refers to the continent that existed prior to that time. Rocks of the Wrangellia Terrane (green) are found in several blocks that are exposed from Denali National Park in Alaska, through British Columbia and all the way into western Idaho. Letters in ovals refer to Accreted Terrane parks listed on the Plate Tectonics and Our National Parks webpage.