Chapter 4 Rocks

Granite contains quartz, orthoclase feldspar, and biotite.

What is a Rock?

It is a mixture of minerals and organic matter.

Rocks are classified into 3 types by how they are formed.

Igneous-cooling magma or lava

Sedimentary- cemented and compacted fragments

Metamorphic-heat and pressure

What are the processes that make or destroy rock?

Weathering

Breaking down of rock by wind, water, ice, heat, animals.

ErosionMoving rocks and sediment from one location to another by wind, water, ice and gravity

Deposition

When moving sediment comes to rest.

Uplift

Upward movement of crust caused by plate movement.

Melting/Cooling of Rock

Occurs near volcanically active areas or deep in Earth’s mantle.

Compaction/Cementation(Lithification)

Hardening of moist sediment by pressure.

Heat and PressurePartial melting of rock by heat of magma chambers or pressure from plate collisions.

Rock Texture

Size of grains- larger or coarse to small or none.

Shape of grains- rounded or jagged

Pattern of grains- layered or non-layered

Classified By:

Section 4-2 Igneous Rocks

Where and how do igneous rocks form?

From cooled lava or magma around volcanic regions.

Igneous rocks are called Intrusive or Extrusive based on where they are formed.

Igneous video 1

Igneous video 2

Intrusive Igneous rocksIntrusive rocks cool slowly and crystals have time to grow larger.

Extrusive RocksExtrusive rock crystals are small because rock was not given enough time to cool.

Magma typesBasaltic(MAFIC)- thin, fast moving lava rich in iron and magnesium. Forms dark colored rocks. (Much like maple syrup)

Granitic (FELSIC)- thick, slow moving magma rich in silicon and oxygen. Forms light colored rocks (More like molasses)

Andesitic- magma with a mixed composition of basaltic and granitic.

Classifying Igneous rock

1. Look at crystal size. Intrusive or Extrusive?

2. Look at color of rock. Basaltic, Granitic or Andesitic?

4-3 Sedimentary Rocks75% of all Rocks on Earth’s surface are sedimentary.

Weathering and Erosion breaks particles into fragments. Particles are either cemented or compacted together to form rock.

Sedimentary rocks contain fossils and give clues to what happened in Earth’s history.

Most rocks found in our area are Sedimentary!!!

Sedimentary video

Types of Sedimentary Rocks

Clastic- rock formed from broken fragments compacted and cemented.

Sediment SizesClastic Sedimentary rocks are classified by sediment size in the rock.

Particles move into an ocean or lake and settle out by particle size and density.

Largest particles near shoreline, finer and smaller farther out.

Sedimentary video #2

Key clastic Sedimentary rocks

shale sandstone conglomerate

Rank the particle sizes of the rocks.

Chemical Sedimentary Rocks

Formed from precipitated solution or evaporated solution. Usually have a smooth texture.

Limestone Chert Rock salt

Organic Sedimentary rocksCompacted remains of once living things such as plants, shells, and microscopic organisms

Coal

CoquinaFossil-rich limestone

Section 4-4 Metamorphic RocksClasses of Metamorphic Rock

•Foliated- mineral grains pressed into layers. Gives rock a “banded” appearance.

•Non-foliated- rock is “baked” and minerals re-arrange

Metamorphic video 1

Which is Foliated/Non-Foliated?

Formation

Regional metamorphism= heat and pressure (extreme folding)

Contact metamorphism= heat (surrounding rock cooked)

Metamorphic video #2

Mother Rocks

Protolith- The rock that a metamorphic rock was formed from. The “Mother Rock”

Sandstone- Quartzite

Limestone- Marble

Granite- Gneiss

Coal Formation

PEAT LIGNITE

BITUMINOUSANTHRACITE

TYPE OF COAL FORMED DEPENDS ON THE AMOUNT OF PRESSURE APPLIED TO MATERIAL!!!!