The stratovolcano is composed mainly of andesite lava flows and breccias and was largely formed prior to the most recent major glaciation (Fraser Glaciation), which occurred between about 25,000 and 10,000 years ago.
Mount Baker (usgs.gov)Snow and ice-covered Mount Baker, located in northern Washington, is the highest peak in the North Cascades (3,286 m or 10,781 ft) and the northernmost volcano in the conterminous United States.