The bulk of the Cascades are made up of the Hozomeen Range. This is all peaks between Ashnola and Silverhope-Skagit Valley, as far north as the Nicoamen Plateau. The rocks composing these peaks are younger than the Okanagan Range. Youngest of the three ranges are the Skagit Range. This is all peaks south of the Fraser and west of the Silverhope-Skagit drainage.
Geologically, the Skagit Range is most similar to the older rocks of the Coast Mountains. The Cascades in general are composed of assemblages of micro-terranes with a wide mix of lithologies. There tends to be more metamorphic, sedimentary, and volcanic rock than is found in the Cascades, and less plutonic, although large areas of granitic rocks are in existance, most notably the Chilliwack Batholith and Needle Peak Pluton.