Shield Volcano:A gently-sloped volcano characterized by lots of lava during eruptions and gentle slopes.
Composite:A volcano built of alternating layers of cinders and lava. Composite volcanoes are characterized by steep slopes and violent eruptions.
Mount Shasta is a composite volcano. Over the last 10,000 years, Mt. Shasta has erupted on average once every 800 years. During the 3,500 years the volcano has erupted about once every 300 years. The most recent eruption may have occurred in 1786 A.D.
Diamond Head is an eroded Cinder (Tuff) Cone. Early sailors mistakenly thought glistening calcite crystals inside the tuff rocks were diamonds, leading to the incorrect name. Diamond Head formed when hot magma rising up a conduit hit ocean water, causing large explosions that threw exploded magma particles (tuff) into a broad ring.
Kohala is a shield volcano. • Kohala is the oldest of the subaerial volcanoes that make up the Island Of Hawaii. Kohala is considered to be extinctbecause it has not erupted for 60,000 years.