Volcanoes Types lava and rocks Cinder Cone Simplest

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 – Slow moving – Sharp edges • Pahoehoe – 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