CHARACTERISTICS OF CHARACTERISTICS OF ROCKSROCKS

1. Rocks are solid.1. Rocks are solid.

2. Most rocks are mixtures of two or 2. Most rocks are mixtures of two or more minerals.more minerals.

3. Some rocks have some materials 3. Some rocks have some materials that were once alive. Coal is a rock. It that were once alive. Coal is a rock. It was formed from dead trees.was formed from dead trees.

4. A rock has no definite ingredients. 4. A rock has no definite ingredients. One part of a rock maybe different One part of a rock maybe different from another part.from another part.

5. Rocks are grouped by the way they 5. Rocks are grouped by the way they were formed:were formed:

•• from volcanoesfrom volcanoes

•• from fine material that has settled, from fine material that has settled, then hardenedthen hardened

•• from heat and pressurefrom heat and pressure

IGNEOUS ROCKSIGNEOUS ROCKS

Rocks that have hardened from liquids Rocks that have hardened from liquids are called igneous rocks. The word are called igneous rocks. The word igneousigneous comes from the Greek word comes from the Greek word for for fire.fire.

All rocks did not cool the same All rocks did not cool the same way. Different speeds of cooling way. Different speeds of cooling made different size crystals.made different size crystals.

·· Slow cooling formed rocks with Slow cooling formed rocks with large crystals.large crystals.

·· Rapid cooling formed rocks with Rapid cooling formed rocks with small crystals.small crystals.

·· Extra-fast cooling formed rocks Extra-fast cooling formed rocks with with no crystals.no crystals.

There are There are three texturesthree textures of igneous of igneous rocks:rocks:

1. 1. Volcanic Igneous RocksVolcanic Igneous Rocks

Extrusive Igneous RocksExtrusive Igneous Rocks No or Small CrystalsNo or Small Crystals Lava Cools QuicklyLava Cools Quickly

2. 2. Plutonic Igneous RocksPlutonic Igneous Rocks Intrusive Igneous RocksIntrusive Igneous Rocks Big CrystalsBig Crystals Magma Cools SlowlyMagma Cools Slowly

3. 3. PorphyriesPorphyries Big and Small crystalsBig and Small crystals

Igneous Rock Igneous Rock ClassificationClassification

Granite Diorite Granite Diorite GabbroGabbro

Rhyolite Andesite BasaltRhyolite Andesite Basalt

(Porphyritic)(Porphyritic)

Intr

usi

veE

xtru

sive

Coarse-grained Fine-grained Coarse-grained Fine-grained PorphyriticPorphyritic

Glassy Vesicular Glassy Vesicular PyroclasticPyroclastic

Igneous Rock Igneous Rock TexturesTextures

SEDIMENTARY ROCKSSEDIMENTARY ROCKS There are forces in nature that keep There are forces in nature that keep

breaking rocks into smaller and breaking rocks into smaller and smaller pieces. These broken pieces smaller pieces. These broken pieces are called are called fragmentsfragments. Pebbles, . Pebbles, gravel, sand, and clay are some gravel, sand, and clay are some kinds of rock fragments.kinds of rock fragments.

Fragments are moved about by Fragments are moved about by water, wind, and frozen waterwater, wind, and frozen water called called glaciersglaciers. The fragments settle . The fragments settle in a new place and begin to pile up. in a new place and begin to pile up. The settled fragments are called The settled fragments are called sedimentsediment. Sediment is always laid . Sediment is always laid down in flat layers. Sediment can down in flat layers. Sediment can harden into solid rock.harden into solid rock.

Sediment can Sediment can harden into harden into sedimentary rocksedimentary rock in two ways: in two ways:

From the From the pressurepressure of its own weight of its own weight by by cementingcementing. Minerals dissolved in . Minerals dissolved in

water glue the sediment togetherwater glue the sediment together

There are There are two texturestwo textures of of sedimentary rocksedimentary rock

1. clastics-conglomerate, sandstone1. clastics-conglomerate, sandstone 2. non-clastics-halite, limestone2. non-clastics-halite, limestone

Clastic rocks–made of cemented Clastic rocks–made of cemented sediments—are classified by their sediments—are classified by their

grain sizes.grain sizes.

http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Sedrocks/Sedrocks9.html

Non-clastic rocks form by chemical Non-clastic rocks form by chemical precipitation (settling out from a precipitation (settling out from a solution.) Limestone is made from calcite, solution.) Limestone is made from calcite, chert from quartz, and halite is rock salt.chert from quartz, and halite is rock salt.

http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Sedrocks/Sedrocks10.html

Sedimentary RocksSedimentary RocksHow They are MadeHow They are Made

Wind and water break down the earthWind and water break down the earth Bits of earth settle in lakes and riversBits of earth settle in lakes and rivers Layers are formed and build upLayers are formed and build up Pressure and time turn the layers to Pressure and time turn the layers to

rockrock

More about sedimentary rocksMore about sedimentary rocks

Shale is the most Shale is the most common common sedimentary rocksedimentary rock

Sedimentary rocks Sedimentary rocks cover about three-cover about three-quarters of the quarters of the land surfaceland surface

For more about For more about sedimentary rocks:sedimentary rocks:http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Sedrocks/Sedrocks1.html

Plant Fragments Are Often Plant Fragments Are Often Visible in CoalVisible in Coal

Breccia

LimestoneLimestone

SandstoneSandstone

ShaleShale

METAMORPHIC ROCKSMETAMORPHIC ROCKS

Heat and pressureHeat and pressure can change can change many things. They can even change many things. They can even change rocks. The name for changed-over rocks. The name for changed-over rocks is rocks is metamorphicmetamorphic rocksrocks. . Metamorphic comes from Greek Metamorphic comes from Greek words meaning words meaning changechange and and form.form.

Metamorphic rocks are formed deep in Metamorphic rocks are formed deep in the earth where there is high the earth where there is high temperature and great pressure. The temperature and great pressure. The heat and pressure change one kind heat and pressure change one kind of rock into another kind of rock. The of rock into another kind of rock. The new rocks become new rocks become harderharder than the than the old rocks. They also old rocks. They also look differentlook different. . Sometimes the Sometimes the mineralsminerals in the in the rocks change too.rocks change too.

How is a metamorphicrock made?

Metamorphic

rocks are made

deep inside the

earth where heat

and pressure

change the rocks as

shown in the picture.

The pressure that changes rocks can The pressure that changes rocks can also also tilttilt and and foldfold them. Folding can them. Folding can lift rocks and make them into high lift rocks and make them into high mountains.mountains.

There are two textures of There are two textures of metamorphic rocksmetamorphic rocks

1. foliated ( layered )1. foliated ( layered ) 2. non-foliated2. non-foliated

Metamorphic RocksMetamorphic Rocks

GneissSchist

The Rock CycleThe Rock Cycle

http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Metrocks/Metrocks2.html

More about sedimentary rocksMore about sedimentary rocks

Shale is the most Shale is the most common common sedimentary rocksedimentary rock

Sedimentary rocks Sedimentary rocks cover about three-cover about three-quarters of the quarters of the land surfaceland surface

For more about For more about sedimentary rocks:sedimentary rocks:http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Sedrocks/Sedrocks1.html

http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Rocks/Rocks8.html

There are two kinds of weathering.There are two kinds of weathering.

1. Mechanical weathering1. Mechanical weathering Disintegration, PhysicalDisintegration, Physical - breaks rocks into smaller and smaller - breaks rocks into smaller and smaller

pieces. It does not change the chemicals pieces. It does not change the chemicals of the rocks.of the rocks.

2. Chemical weathering2. Chemical weathering DecompositionDecomposition - also breaks rocks into smaller pieces. It - also breaks rocks into smaller pieces. It

changes the chemicals of the rocks.changes the chemicals of the rocks.

WeatheringWeathering breaks rocks into breaks rocks into smaller pieces. It does not carry smaller pieces. It does not carry away the fragments. away the fragments. ErosionErosion carries the fragments away.carries the fragments away.

CHEMICAL WEATHERING CHEMICAL WEATHERING (DECOMPOSITION)(DECOMPOSITION)

Chemical weathering breaks up rocks Chemical weathering breaks up rocks and changes the chemicals of the and changes the chemicals of the rocks.rocks.

Most Most chemical weatheringchemical weathering is is caused by the actions of caused by the actions of oxygenoxygen, , rain waterrain water, or , or carbon dioxide.carbon dioxide.

1. Oxygen1. Oxygen in the air links up with some in the air links up with some of the elements in rocks. The link-up of the elements in rocks. The link-up forms oxides. The oxides break away forms oxides. The oxides break away from the rocks.from the rocks.

One One oxideoxide that you know is rust. that you know is rust. 2. Rain water2. Rain water can change minerals in can change minerals in

two ways. A) It dissolves some minerals. two ways. A) It dissolves some minerals. B) Water links up with other minerals.B) Water links up with other minerals.

3. Carbon dioxide3. Carbon dioxide in the air dissolves in the air dissolves easily in rain water. This forms carbonic easily in rain water. This forms carbonic acid. Acids dissolve limestone.acid. Acids dissolve limestone.

Plant WedgingPlant Wedging

Limestone Limestone cave cave

featuresfeatures

chemical chemical weatherinweatherin

gg

Streams and ErosionStreams and Erosion

Glacier ErosionGlacier Erosion

Mechanical Weathering or Mechanical Weathering or Disintegration or Physical Disintegration or Physical WeatheringWeathering

There are four main causes:There are four main causes:

1.1. Temperature ChangeTemperature Change

2.2. Frost ActionFrost Action

3.3. Root ActionRoot Action

4.4. Animal ActivityAnimal Activity

Water Erosion

Root GrowthRoot Growth

OxidationOxidation