Yamsay, along with the Simcoe volcanic complex, Medicine Lake Highlands, and Newberry Volcano, make up a wayward range of shield volcanoes between and east of the main Cascade Range. Volcanism at these centers is unlike other eruptions in the Cascades, and it does not stem from fissures as would Basin and Range volcanism. The volcanoes appear to be isolated from the major volcanic ranges in the Northwestern United States, although scientists group them as part of the Cascades.