Download - Rock cycle
2.20.13
Article Review due Friday
Moving in on 1 week to finish up your project.
Review
Describe the sorting of elements in Earth’s crust
Relate mantel convection to the theory of plate tectonics and provide evidence for the theory.
Compare and contrast types of plate contact
Question
How do minerals cycle?
Objectives
Describe the path of minerals through the rock cycle.
Compare and contrast igneous, sedimentary, and metamorphic rocks.
Differentiate between weathering and erosion.
The Rock Cycle
What was the name of the cycle that we talked about the other day?
Tectonic Cycle
Remind me what that is
The Rock Cycle
Rock Cycle: Constant formation and destruction of rock
Slowest of all of Earth’s cycles
The Rock Cycle
If you had to define the term “rock” how would you do it?
Rocks are composed of minerals
So the question is, what is a mineral?
The Rock Cycle
Mineral Characteristics
Solid
Uniform crystalline structure
Form under specific temperature and pressure
Generally compounds
The Rock Cycle
We are going to move through the rock cycle using the formation of each of the 3 major types of rock.
Each type of rock represents a step in the cycle.
Does anyone known the three types of rock?
The Rock Cycle
Igneous
Sedimentary
Metamorphic
The Rock Cycle
Igneous
First step in the cycle
Forms from cooled magma
Classified as basaltic or granite and intrusive or extrusive
The Rock Cycle
Igneous
Basaltic - dark colored, high concentration of dense elements, forms oceanic crust
Granite - light color, lighter elements, forms continental crust
The Rock Cycle
Igneous
Intrusive - magma cools underground. Slow cooling leads to large crystals and coarse texture
Extrusive - cools quickly on the surface. Quick cooling leads to small crystals and a smooth texture
The Rock Cycle
Once rocks are on the surface, what are the subjected to?
The elements
What do you think the elements do to the rocks?
Break them down
The Rock Cycle
Weathering vs. Erosion
Weathering - the breakdown of a rock
Erosion - the transport of sediments that result from weathering
The Rock Cycle
Weathering
Two types
Physical - physically breaks down the rock
No chemical change
Chemical - chemically changes the rock composition
The Rock Cycle
Weathering
Physical Weathering
How might a rock be broken down physically?
The Rock Cycle
Weathering
Freeze/thaw
Ice wedging
Abrasion
Biological action
The Rock Cycle
Chemical
Chemical reactions lead to degradation
Can be sped up by physical weathering
Primary minerals react to form secondary minerals
The Rock Cycle
Chemical
What could lead to chemical weathering?
Water dissolving minerals
Lichen dissolving rock
Acid Precipitation
The Rock Cycle
Erosion
The transport of sediments produced by weathering
Accomplished by
Wind
Water
Ice
The Rock Cycle
Erosion
When the erosive force stops deposition occurs
Deposition - accumulation of transported material
Human activities can greatly enhance erosion
The Rock Cycle
Sedimentary rock
What is the term for the accumulation of sediment?
As sediment collects, what do you think happens to the bottom of the pile?
The Rock Cycle
Sedimentary rock
Lower layers of a sediment pile are subject to tremendous pressure
Pressure causes grains to cement together
Forms sedimentary rock
The Rock Cycle
Sedimentary rock
Generally has a layered appearance
Why?
The Rock Cycle
Metamorphic Rock
Forms when rock is exposed to extreme heat and pressure
Where might this occur?
The Rock Cycle
Metamorphic Rock
Continental boundaries
Areas with a large load of overlaying rock layers
Exp. marble and slate
Often used as building materials
The Rock Cycle
Why would sedimentary rock be the only type of rock that contains fossils?
Why would metamorphic rock be good for building?