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?