Types of Volcanoes

Cinder cones are the most widespread type of volcano.  Also called Scoria cones, they are the smallest variation, with heights that rarely go over 1,000 feet.

            Properties:

            -Made up almost entirely of basaltic tephra, which builds up around the opening to create the cone.

            -Usually have steep slopes, up to 35 degrees; older, eroded cones can be anywhere from 15 to 20 degrees in slope.

             -They have straight sides and rather large crates at the peak, for their size.

            Sunset Crater which is a cinder cone

Shield volcanoes are low-slung and wide volcanoes with bases that can extend to miles in diameter.

            Properties:

            -Generally balsatic in their lava composition, they are formed by the gentle spreading of basaltic lava from the summit                   area over a large area.

            -The slope of the sides is usually very gentle (2-3 degrees), but does get steeper as the slope approaches the middle (up               to about 10 degrees) and flattens out at the top.

            -Examples are Hawaiian and Icelandic volcanoes.

  Mauna Loa on Hawaii

Composite cones, or stratovolcanoes, are the most diverse group in shape and makeup, and also the deadliest. 

            Properties:

            -Slopes tend to start gently, but veer upward towards the crater, which is usually relatively small.

            -Can be formed by a mixture of lava flow, tephra falling from the air, and debris, thus forming many shapes.

            -Average composition is andestite; can change go through the whole spectrum of lava (basaltic to rhyolite) in a single               eruption.

            -Mountains such as Mt. St. Helens in the United States and Mt. Fuju in Japan are examples of composite cone               volcanoes.

Mt.Mayon which is a composite cone