• a_geologistMagma Monday: Dark, basaltic lava flow erupted from a cinder cone (in lower left). Cinder cones are relatively small, short-lived volcanoes (life span a few months to a few years only) of basaltic composition. During the cone building phase, a lot of gases (water and CO2 mostly) cause the eruption to be somewhat explosive, producing a lot of fragmental material, like cinder. But after the gases are lost, the magma loses its fizz and then tends to come out as non-explosive lava flows, as seen here. (Diameter of cone about 1 km. San Francisco volcanic field north of Flagstaff, Arizona. Image from Google Earth)

Kenna by Liz Osban