ROCK CYCLE
What processes change rock?
1. Weathering, erosion, and deposition.
a. Weathering – breaks down rocks into
sediments ( rain, freezing, snow)
b. Erosion – moving of that sediment
(wind, water, ice, gravity)
c. Deposition – when sediment comes to a
rest
2. Temperature and Pressure
What are the Classes of Rock?
1. Sedimentary: sediment from older rocks is
pressed (compaction) and/or cemented
together.
a. Clastic: form when sediments are
buried, compacted, and cemented
b. Chemical: form when water evaporates
c. Organic: composed from the fragmented
remains of ocean animals, plants (fossils)
2. Igneous:
a. forms from magma and lava,
b. As the rock cools, crystals form:
i. cools quickly = small crystals and
sometimes tiny holes throughout it
ii. cools slowly= large crystals
c. Extrusive Igneous Rocks: form at or
above the earth’s surface
d. Intrusive Igneous Rocks form BELOW the
earth’s surface
3. Metamorphic : temperature (heating) and
pressure (squeezing) and/or chemical
reactions.
a. Foliated: Mineral grains (crystals) line
up in parallel distorted bands
b. Non foliated: no bands or lines
What is the rock cycle?
The series of processes in which rock changes from
one rock type to another.
Igneous: at earth’s surface can weather and
erode to form sedimentary rock, or
may turn into metamorphic rock
when already below earth’s surface
and undergoes heating and
squeezing
Sedimentary: temperature and pressure can
turn it into metamorphic, or may
melt and become igneous
Metamorphic: can melt to form magma,
when cools will become igneous,
and it can be broken down by
weathering and erosion to form
sedimentary rock
How do tectonic plate motions affect the rock
cycles?
1. By moving rock up and down – uplift (rising
of region of the crust to higher elevation
and subsidence (sinking of regions of crust
to lower elevations – forms basins where
sediment can deposit)
2. By pulling apart earth’s surface – rift zone
(an area where a set of deep cracks form)
Essay questions:
1. Is metamorphic rock the only type of rock
that serves as a source of material for making
magma?
2. How does the conversion of sediments into
rock DIFFER from the conversion of
sedimentary rock into metamorphic rock?
Key words to use: pressure, cementing,
temperature