Medicine Lake volcano is situated just east of the Cascade Volcanic Arc axis in northern California’s high desert 55 km (35 mi), northeast of Mount Shasta. Also known as the Medicine Lake Highland, this shield-shaped volcano together with its surrounding apron of lavas covers a total area of about 2,200 km² (850 mi²), extending approximately 80 km (50 mi) north-south and 50 km (30 mi) east-west. A shallow, but wide (7x12 km, 4.3x7.5 mi) caldera basin containing its namesake lake is located at the summit of the volcano. Medicine Lake volcano has had intermittent eruptive periods over the last half-million years producing mostly basalt to andesite lava flows and cinder cones with occasional dacite to rhyolite lava flows and tephras. The most recent volcanic activity occurred about 950 years ago and formed Glass Mountain, a 1 km³ (1/4 mi³) dacite and rhyolite obsidian flow that erupted just outside the eastern caldera rim. Lava Beds National Monument is located on the northern flank of Medicine Lake volcano and encompasses mostly basaltic lavas that host spectacular lava-tube caves and form other well-preserved young volcanic features.

Location: California, Siskiyou & Modoc Counties
Latitude: 41.611° N
Longitude: 121.554° W
Elevation: 2,412 (m) 7,913 (f)
Volcano type: composite (red map area)
Composition: basalt to rhyolite
Most recent eruption: 950 years ago
Nearby towns: Malin, Merrill, Tulelake, Klamath Falls (OR)
Alert Level: Normal