460 likes | 648 Views
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
E N D
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
Lava Dome • Formed by lava that is too thick to flow any large distance • Lava piles around the vent
Types of lava • AA • Slow moving • Sharp edges • Pahoehoe • Fast moving • Smooth edges • Pillow • Form under water • If on land is evidence that was once under water
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
Rhyolite • Extrusive rock, formed on the surface • Light colored silicates like granite • Cool rapidly
Andesite • Medium-grey color • Fine grain size • From volcanos
Diorite • Intrusive rock, forms underground • Coarse-grained • No visible quartz crystals • Dark color
Basalt • Dark colored • Small crystals • Usually formed above ground from volcanic origins • A lot of deposits in Oregon and Washington
Gabbro • Forms underground • Dark green to black color • Makes up a lot of oceanic crust
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
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
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