Volcanoes Types, lava, and rocks
Cinder Cone Simplest type Built from volcanic debris from a single vent Most have bowl shaped crater Height reaches about 1000 ft above their surroundings
Parícutin in 1994 Mexico Formed over 9 years
Composite or Stratovolcano Steep sided Symmetrical cone Alternating layers of ash, lava, cinder blocks Can be over 8000 ft tall Have crater with central vent
Famous composite volcanos Mount Fuji in Japan Mount Cotopaxi in Ecuador Mount Shasta in California Mount Hood in Oregon Mount St. Helens and Mount Rainier in Washington.
Shield Volcano Entirely built of lava Gently sloping sides Looks like warrior's shield from the side
Mauna Loa
Lava Dome Formed by lava that is too thick to flow any large distance Lava piles around the vent
Kelud Volcano
Types of lava AA Pahoehoe Pillow Slow moving Sharp edges Fast moving Smooth edges Pillow Form under water If on land is evidence that was once under water
AA lava
AA lava
Pahoehoe
Pahoehoe
Pillow Lava
Pillow Lava
Rocks that form from volcanos
Igneous rocks Rocks that form from lava Can cool either quickly or slowly The way they cool will impact their structure 2 types – intrusive and extrusive
Granite Best know of all igneous rocks Mixture of different types of rocks Formed underground
Granite
Rhyolite Extrusive rock, formed on the surface Light colored silicates like granite Cool rapidly
Rhyolite
Andesite Medium-grey color Fine grain size From volcanos
Andesite
Diorite Intrusive rock, forms underground Coarse-grained No visible quartz crystals Dark color
Diorite
Basalt Dark colored Small crystals Usually formed above ground from volcanic origins A lot of deposits in Oregon and Washington
Basalt
Gabbro Forms underground Dark green to black color Makes up a lot of oceanic crust
Gabbro
Obsidian Volcanic glass Cools very quickly Black or green in color Can have very sharp edges when broken Used as tools for centuries because of sharpness and hardness
obsidian
Pumice glassy texture Formed with large amount of gas makes frothy mixture Many pieces will float in water Many people use it to smooth out and remove dead layer of skin
Pumice
Scoria Heavier than pumice Made of frothy lava with less air Usually red in color Used in gas grills to help with distribution of heat
Scoria