Transcript Metamorphic rock - North Las Vegas

Types of metamorphic rocks
0 Heat and pressure deep beneath Earth’s surface can
change any rock into metamorphic rock.
0 Geologists classify metamorphic rocks according to
the arrangement of the grains that make up the rocks.
Foliated rock
0 Metamorphic rocks that have their grains arranged in
parallel layers or bands.
0 They split in layers.
0 Foliated rocks include: slate, schist, gneiss
0 Slate comes from heat and pressure changing the
sedimentary rock shale. Slate is a denser more
compact version of shale.
Nonfoliated rocks
0 The mineral grains in these rocks are arranged
randomly.
0 These do not split in layers.
0 Marble and quartzite are two metamorphic rocks that
are non-foliated.
0 Quartzite comes from sandstone. The quartz particles
recrystallize to form quartzite.
Rock cycle
0 Forces deep inside Earth and at the surface produce a
slow cycle that builds, destroys, and changes the rocks
in the crust.
0 Is a series of processes on Earth’s surface and in the
crust and mantle that slowly change rocks from one
form to another.
Beginning
0 In the case of stone mountain, the rock cycle began
millions of years ago.
0 First a huge piece of granite formed underground.
0 Then the mountain building slowly pushed the granite
upward.
0 Over millions of years weathering and water began to
wear away the granite, forming sediment.
Continuing
0 Over millions of years, layers of sandy sediment pile
up on the ocean floor.
0 Slowly the sand will compact by its own weight.
0 Dissolved calcite will cement the particles together.
0 Eventually that granite will form into sandstone, a
sedimentary rock.
Continuing
0 More and more sediment will pile up on the
sandstone. As it becomes buried pressure will
increase.
0 The rock will become hot.
0 Silica will replace the calcite holding the rock together
and the texture will change from gritty to smooth.
0 After millions of years the sandstone will change into
quartzite (metamorphic rock)
Rock cycle