Volcanic Eruptions
Describe pyroclastic material and lava flows
What is pyroclastic material ?
Volcanic ash and volcanic dust.
Volcanic ash is pyroclastic particles that are less than 2mm in diameter. Volcanic dust is volcanic ash that is less than 0.25mm in diameter.
Lapilli
Large pyroclastic particles that are less then 64mm in diameter.
Volcanic bombs and volcanic blocks
Volcanic bombs spin through the air, they cool and developable round or spindle shape. Volcanic blocks form from solid rock that is blasted from the vent.
Mafic types of lava
Pahoehoe
Pahoehoe is the lest viscous type of mafic lava.it forms wrinkly volcanic rock when it cools.
Aa
Aa lava is more viscous than pahoehoe lava and forms sharp volcanic rock when It cools.
Blocky lava
Blocky lava is the most viscous type of mafic lava and forms chunky volcanic rock when it cools.
Lava Flows
Describe the three different types of volcanos
Cinder cones
A type of volcano that has a very steep slopes. The slopes are rarely more than a few hundred meters high. Cinder cones form from explosive eruptions and are made out of pyroclastic material.
Shield volcanoes
Volcanic cones that are broad at the base and have a gently sloping sides. A shield volcano covers a wise area and generally forms from quiet eruptions. Layers of hot,Mafic lava flow out around the vent, harden, and slowly build up to form the cone.
Composite volcanoes
Composite volcanoes are made up of alternating layers of harden lava flows and pyroclastic material. During a quiet eruption,lava flows cover the sides of the cone. Ten, when an explosive occurs, large amount f pyroclastic material are deposited around vent. Composite volcanoes are also known as stratovolcanoes, commonly develop to form large volcanic mountains.