Metamorphic Rocks
I
Metamorphic rocks are formed from
existing rock (sedimentary, igneous,
metamorphic) by the action of heat, pressure,
and chemicals.
II Metamorphism- the process of forming
metamorphic rocks within the lithosphere,
making the rocks more dense and less porous.
a) Recrystallization- is the process of
increasing the size of the mineral
crystals and/or changing the mineral
composition without melting.
b) Foliation- parallel layers of minerals
caused by pressures on the rock.
c) Two Types:
1)
Regional metamorphism- when large
areas of rock are under intense heat
and pressure causing them to change
form. (results in foliation)
2)
Contact metamorphism occurs when
hot magma forces its way into
overlying rock and bakes the rocks in
contact with it.
a)Change in the rock is less drastic
(no foliation) and less rock is
affected then in regional.