Unit 3 - Volcanoes & Earthquakes Flashcards
be able to lable batholith, stock, laccoliths, dike, sill
Label the vent and the crater
oki
How is a caldera different from a crater?
a calderea is a depression that hapens when the side of the volcano collapses in on its magma chamber whe the crater bowl shape around the vent
What causes a caldera to form?
collapses in on its magma chamber
At what temperatures do most rocks melt?
800 degrees- 1200 degrees
If rocks contain water, how is the melting point affected?
it melts at a lower temperature
Identify these two common types of igneous rock:
Which cooled slowly and which cooled quickly? How can you tell?
Which cooled underground and which came out of the volcano?
obsidian: quickly . extrusive
granite: cooled slowly (time to crystals) intrusive
What is viscosity?
the tendency of liquid to resist flow
How does temperature affect viscosity?
hot= less viscous
If the lava coming from a volcano has a high silica content, is the volcano more explosive or less explosive?
more
What is tephra?
rock fragments thrown into air during eruption
Below is a list of types of tephra that can erupt from a volcano. Number them from smallest to largest:
_____ bombs ______ ash ______ lapilli _______ dust
4 bombs 2 ash 3lapilli 1 dust
What is pyroclastic flow?
rapidly flowed and cloud of gas, and tephra
Describe the shape of of these types of volcanoes:
cinder cone:
shield volcano:
composite volcano (stratovolcano):
cinder cone: steep violently ejected lava
shield volcano: broad base, slope sides
composite volcano: fragment and layers of lava
Which type of volcano in Question 8 is produced by:
eruption of thin, nonviscous lava-
alternating layers of lava and tephra –
eruption of thick viscous lava –
sheild
composite
cinder cone
What causes most volcanoes to form?
movement of crust at plate boundry