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Terms in this set (84)

Volcanoes only give a hint to what's going on on surface
(magma pushed its way into cracks underneath, is squeezed between rock layers and giant masses of lava solidify under the surface)
Any igneous intrusion a rock mass that forms when magma cools inside earth's crust is called= pluton
Sills—sheets of magma that pushed themselves into previously formed rock
Lies parallel(horizontal) to layer it intruded
Formed when magma forced between not across rock layers
100's of meters thick and many km's long
Example...Palisades, Hudson River, NY,NY
Dikes--sheets of magma that pushed themselves into previously formed rock
Cuts across rock vertically or at a steep angle
Formed when magma intrudes into angled rocks
Can be 100's of km's in height and range from a centimeter to many meters thick.
Dikes common in regions of volcanic activity
Laccoliths—hardened magma located close to the surface that instead of spreading out into sheets, they bulge upwards to form domes.
Rock layers above laccolith also pushed upwards to form a dome.
Volcanic Neck
As an inactive volcano erodes, a volcanic neck may be exposed
This is the central plug of hardened magma left after volcanic material around it has worn away.
Batholiths
Largest of all plutons
Forms the cores of many of Earth's mt. ranges.
Usually made of granite and can span tens of thousands square kilometers.
It becomes exposed thru uplift and erosion of overlying rock layers
A smaller batholith exposed at the surface is called a stock
Largest batholith in N. America forms core of the Coast Range in Alaska and British Columbia

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