The Rock CycleThe Rock Cycle

Chapter 4Chapter 4

Mrs. Veurink’sMrs. Veurink’s

Earth ScienceEarth Science

What is a ROCK?What is a ROCK?

• A rock is a naturally

occurring solid mixture of one

or more minerals and

organic matter

When classifying a rock sample geologists observe the rock’s color and texture and determine its mineral composition.Texture: the size, shape, and pattern of the rock’s grain.Color: the apparent color of the rock, on the inside and the outside.Mineral composition: The minerals that make up the different parts of a rock.

Three different rock Types:

Igneous rock forms when magma cools and makes crystals. Magma is a hot liquid made of melted minerals. When magma pours onto the earth’s surface it is called lava. The minerals can form crystals when they cool. Igneous rock can form underground, where the magma cools slowly. Or, igneous rock can form above ground, where the magma cools quickly.

INTRUSIVE IGNEOUS ROCKS – When igneous rocks are formed by magma that cools BENEATH Earth’s surface. example-GraniteEXTUSIVE IGNEOUS ROCKS – When igneous rocks are formed by LAVA ON Earth’s surface. example- basalt

2 Types of Igneous Rocks2 Types of Igneous Rocks

Igneous Rock ExamplesIgneous Rock Examples

Basalt Granite

Sedimentary rocks form from particles deposited by water and windIf you have ever walked along a beach (which I am sure you have) you may have noticed tiny sand grains, mud, and pebbles.These are some sediments that eventually form into sedimentary rocks

• Clastic- made of fragments of rocks cemented together by a mineral such as calcite or quartz. Example - Conglomerate

• Chemical- forms from solutions of dissolved minerals and water. Example –Halite

• Organic- forms from the remains or fossils of animals that once lived in the ocean. Example- Fossiliferous limestone

Three types of Three types of Sedimentary RockSedimentary Rock

Sedimentary Rock PicsSedimentary Rock Pics

Conglomerate Halite Fossiliferous Limestone

Sedimentary Rocks : Sedimentary Rocks : Weathering or ErosionWeathering or Erosion

Destructive forces are constantly breaking up and wearing away all the rocks on Earth’s surfaceThe forces include heat and cold, rain, waves, and grinding iceErosion occurs when running water or wind loosens and carry away the fragments of rock.This forms- SEDIMENT

Sedimentary Rocks: Sedimentary Rocks: DepositionDeposition

Eventually, the moving water or wind slows and deposits the sediment.

If water is carrying the sediment, rock fragments and other materials sink to the bottom of a lake or ocean.

In addition to particles of rock, sediment may include shells, bones, leaves, stems, and other remains of living things. These may become fossils.

Sedimentary Rocks: Sedimentary Rocks: CompactionCompaction

• Compaction is the process that presses sediments together.

• Year after year more sediment falls on top, creating new layers. This is called stratification.

• The weight of the layers further compacts the sediments, squeezing them tightly together.

• The layers often remain visible in the sedimentary rock and are called STRATA.

 While compaction is taking place, the minerals in the rock slowly dissolve in the water. The dissolved minerals seep into the spaces between particles of sediment. Cementation is the process in which dissolved minerals crystallize and glue particles of sediment together. This finally forms the sedimentary rock.It often takes millions of years for compaction and cementation to transform loose sediments into solid sedimentary rock.

Sedimentary Rocks: CementationSedimentary Rocks: Cementation

Erosion (Weathering) and Deposition: water or wind deposits sedimentsCompaction: The heavy sediments press down on the layers beneathCementation: Dissolved minerals flow between the particles and cement them together

Sedimentary TransformationsSedimentary Transformations

Metamorphic rocks are rocks that have "morphed" into another kind of rock. These rocks were once igneous or sedimentary rocks. How do sedimentary and igneous rocks change? The rocks are under tons and tons of pressure, which fosters heat build up, and this causes them to change.

Metamorphic Rock PicsMetamorphic Rock Pics

There are two types of Metamorphic Rocks

•Foliated- mineral grains are arranged in bands

•Nonfoliated- grains not arranged in bands

Gneiss

Slate

Bet Cha’ Weren’t Expecting A….Bet Cha’ Weren’t Expecting A….POP QUIZ!!!!!POP QUIZ!!!!!**

1. Which type of rock has been formed by magma or lava?

2. What are the three types of rock?3. What do we classify rocks by?4. How do sedimentary rocks form (in order)?5. Metamorphic rocks are rocks that have

?(fill in the blank)6. What is the process in which sedimentary

rocks are arranged in layers?7. What does “ignis” mean in the word igneous?

*Answers are on next slide!

ANSWERS!!!!ANSWERS!!!!

1. Igneous, Sedimentary, and Metamorphic2. Igneous3. Texture, Color, and Mineral Composition4. Erosion, Deposition, Compaction,

Cementation5. Morphed6. Stratification7. “ignis” means FIRE

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