Transcript The Rock Cycle - Treynor Schools

The Rock Cycle
What is a rock?
Answer
• A naturally occurring solid mixture of 1 or
more minerals/organic matter
• Rocks are always changing
• New rocks form from old rocks = ROCK CYCLE
How can rocks help Humans?
HMMMMMMM…
Human Usage of Rocks
• Used for tools
– Hammers, knives, arrowheads, spear points,
scrapers
• Roads + monuments
– Pyramids, capitol buildings
Weathering
• IS H2O, wind, ice, and heat break down rock
• Breaks rocks down into fragments
• These fragments will become part of
sedimentary rocks
Erosion
• Sediment is removed from its source
• This is caused by H2O, wind, ice, + gravity
Deposition
• Process in which sediment moved by erosion
is dropped and comes to rest is this.
• Sediment is deposited in bodies of water or
areas of low-lying land
• Sediment will be pressed and cemented
together to form sedimentary rock
Example of this
• Bryce Canyon is an example of weathering,
erosion, and deposition
Heat and Pressure
• Sedimentary rock can also form when
sediment is buried and squeezed by weight
• IF add heat to the process then the sediment
rock can change to metamorphic rock
• If HOT enough to melt then will create magma
when MAGMA cools then have igneous rock
Uplift
• Buried rock will eventually be exposed to
Earth due to uplift and erosion
• Uplift is movement within the Earth that
causes rocks inside the Earth to be moved to
the surface
• Uplifted rocks will then go through
weathering, erosion, and deposition
Rock cycle steps/paths
1. sedimentary rock
-grains of sand and other sediments erode from hills
and Mts—wash into rivers—oceans—form the
ocean floor—compacted together to form this
2. Metamorphic rock
-Earth’s crust collide (tectonic plates) some rock is
forced downward—get intense heat + pressure=
m. Rock
3. Magma
-Hot Liquid forms when rock is melted
4. Igneous Rock
-Magma rises (is less dense), cools= I. rock
5. Sediment
-Uplift and Erosion expose the Igneous
Rock—weathers, wears back into
Sedimentary rock
Rocks changing
• So rocks are continually changing what time
they’re due to the Earth’s process
– Igneous –Sedimentary-Metamorphic
• The location of the rock is a huge factor is
what the rock will change into
– Surface- have weathering, erosion, deposition
– Deep down- heat and pressure
Rock Classification
• Rocks are first divided into igneous,
metamorphic, and sedimentary by how they
form
• But then will divided them down even farther
– Ex. Igneous- if cooled on Earth’s surface or below
• 2 main items scientist use is the composition
and texture of rock to identify them
Composition
• Minerals that make up the rock
• Look @ pg. 95
Texture
• The size, shape, and position of the grains that
make up the rock = texture of it
– Sedimentary= fine-medium, or coarse- depends
on size of grains
– Igneous= fine to coarse-depends on how time
magma has to cool
– Metamorphic = fine or coarse- depends on
temperature and pressure rock gets
– Texture can also tell how rock was formed-look on
pg. 96