Mazama and Crater Lake form part of the Mazama reach of the Oregon Cascades, which stretches for from Timber Crater to the Big Bunchgrass shield volcano. This includes 175 Quaternary volcanic vents within a belt that ranges from in width, which has a high vent density with many shields and monogenetic volcanic centers. After Newberry Volcano, Mazama is the second largest Quaternary volcanic edifice in Oregon, and the most voluminous, with an overall volume of . Mazama is the newest of the Quaternary calderas in the Cascade Volcanic Arc, which also include the Newberry calderas and the caldera at the Medicine Lake Volcano. Quaternary monogenetic volcanism throughout Oregon's High Cascades includes cinder cones, lava fields, and small shield volcanoes, which have produced lava ranging from low-potassium, high-alumina olivine tholeiite to medium-potassium calc-alkaline basalt, basaltic andesite to shoshonitic basaltic andesite.