the past 10,000 years” (Scarth 1994).The shapes of most Lava domes are determined by the way they grow and solidify. They grow from below when viscous lava wells up the vent and then solidify from their outer layers inwards. As the dome formsthere is a conflict between the upward-surging, plastic mass and the solid, outer shell of brittle rock, which prevent expansion. Great upsurges can overcome the strength of the outer shell and cause its crest to burst open and emit molten material, while at the same time gas is also released. The appearance of a dome ultimately depends on the interplay of upwelling, explosion and solidification. The Novarupta Dome, which formed during the 1912 eruption of the Katmai Volcano in Alaska, measured 800 feet across and 200 feet high. The internal structure of Novarupta indicated by the layering of lava fanning upward and outward from the center shows that it grew largely by expansion from within. Figure 3: The Novarupta Dome formed during the 1912 eruption of the Katma VolcanoCinder Cones Figure 4: Schematic representation of the Internal structure of a typical cinder coneCinder cones are among the most common volcanic landforms found in the world and are also the simplest type of volcano. They are built from particles and blobs of congealed lava ejected from a single vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as cinders around the vent to form an oval cone. Cinder cones are mostly produced by Strombolian eruptions. They commonly grow in groups and are often found on fissures or in swarms, in both oceanic environments and continental environments. Shield VolcanoShield volcanoes are built up of almost entirely of fluid lava. Flow after flow pours out in all directions from a central summit vent, or group of vents. This builds a broad, gently sloping cone of flat, domical shape, with a profile much...
