Go to the following website and click on Volcano photos to observe the various volcanic shapes and parts: www.volcanodiscovery.com
(a)
• Cinder cone: Cinder cones are the smallest type of volcano, rarely reaching heights of more than 300 m. They are the most common type of volcano found on Earth. Cinder cones consist of pyroclastic material formed from relatively explosive eruptions. Cinder cones have very steep sides with a wide crater at the summit. While many volcanic cones erupt many times, cinder cones usually erupt only once in their lifetime as the eruption destroys their structure. They are usually found surrounding shield volcanoes and composite cones. For example, there are more than 100 cinder cones surrounding Mauna Loa in Hawaii.
Crater Pyroclastic material
: ) Fig. 3.12 (a) A cinder cone volcano and (b) a cross-section of a cinder cone
(b)
Vent (a) Shield Volcano
Shield volcanoes usually form at hotspots, and occasionally at constructive plate boundaries. Shield volcanoes form from gentle eruptions where basic lava reaches the surface and spreads out over a large area. Layers of lava build up very slowly to form a volcanic mountain with gently sloping sides. The base of the volcano can be more than 100 km in diameter. An example is Mauna Kea in Hawaii.
Summit caldera Central vent Lava flow (b)
: ) Fig. 3.13 (a) Mauna Kea in Hawaii and (b) a cross-section of a shield volcano
