CHARACTERISTICS OF ROCKS 1. Rocks are solid.

2. Most rocks are mixtures of two or more minerals. 2. Most rocks are mixtures of two or more minerals. 3. Some rocks have some materials that were once alive. Coal is a rock. It was formed from dead trees. 3. Some rocks have some materials that were once alive. Coal is a rock. It was formed from dead trees.

4. A rock has no definite ingredients. One part of a rock maybe different from another part. 5. Rocks are grouped by the way they were formed: from volcanoesfrom volcanoes from fine material that has settled, then hardenedfrom fine material that has settled, then hardened from heat and pressurefrom heat and pressure

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

All rocks did not cool the same way. Different speeds of cooling made different size crystals. ·Slow cooling formed rocks with large crystals. ·Slow cooling formed rocks with large crystals. ·Rapid cooling formed rocks with small crystals. ·Rapid cooling formed rocks with small crystals. ·Extra-fast cooling formed rocks with no crystals. ·Extra-fast cooling formed rocks with no crystals.

There are three textures of igneous rocks: 1. Volcanic Igneous Rocks 1. Volcanic Igneous Rocks Extrusive Igneous Rocks No or Small Crystals No or Small Crystals Lava Cools Quickly Lava Cools Quickly

2. Plutonic Igneous Rocks Intrusive Igneous Rocks Intrusive Igneous Rocks Big Crystals Big Crystals Magma Cools Slowly Magma Cools Slowly

3. Porphyries Big and Small crystals Big and Small crystals

Igneous Rock Classification Granite Diorite Gabbro Granite Diorite Gabbro Rhyolite Andesite Basalt Rhyolite Andesite Basalt (Porphyritic) (Porphyritic) Intrusive Extrusive

Coarse-grained Fine-grained Porphyritic Glassy Vesicular Pyroclastic Glassy Vesicular Pyroclastic Igneous Rock Textures

SEDIMENTARY ROCKS There are forces in nature that keep breaking rocks into smaller and smaller pieces. These broken pieces are called fragments. Pebbles, gravel, sand, and clay are some kinds of rock fragments. There are forces in nature that keep breaking rocks into smaller and smaller pieces. These broken pieces are called fragments. Pebbles, gravel, sand, and clay are some kinds of rock fragments.

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

Sediment can harden into sedimentary rock in two ways: From the pressure of its own weight From the pressure of its own weight by cementing. Minerals dissolved in water glue the sediment together by cementing. Minerals dissolved in water glue the sediment together

There are two textures of sedimentary rock 1. clastics-conglomerate, sandstone 1. clastics-conglomerate, sandstone 2. non-clastics-halite, limestone 2. non-clastics-halite, limestone

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

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

Sedimentary Rocks How They are Made Wind and water break down the earth Wind and water break down the earth Bits of earth settle in lakes and rivers Bits of earth settle in lakes and rivers Layers are formed and build up Layers are formed and build up Pressure and time turn the layers to rock Pressure and time turn the layers to rock

More about sedimentary rocks Shale is the most common sedimentary rock Shale is the most common sedimentary rock Sedimentary rocks cover about three- quarters of the land surface Sedimentary rocks cover about three- quarters of the land surface For more about sedimentary rocks: For more about sedimentary rocks:

Plant Fragments Are Often Visible in Coal

Breccia

Limestone

Sandstone

Shale

METAMORPHIC ROCKS Heat and pressure can change many things. They can even change rocks. The name for changed-over rocks is metamorphic rocks. Metamorphic comes from Greek words meaning change and form. Heat and pressure can change many things. They can even change rocks. The name for changed-over rocks is metamorphic rocks. Metamorphic comes from Greek words meaning change and form.

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

How is a metamorphic rock 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 also tilt and fold them. Folding can lift rocks and make them into high mountains. The pressure that changes rocks can also tilt and fold them. Folding can lift rocks and make them into high mountains. There are two textures of metamorphic rocks There are two textures of metamorphic rocks 1. foliated ( layered ) 1. foliated ( layered ) 2. non-foliated 2. non-foliated

Metamorphic Rocks Gneiss Schist

The Rock Cycle

More about sedimentary rocks Shale is the most common sedimentary rock Shale is the most common sedimentary rock Sedimentary rocks cover about three- quarters of the land surface Sedimentary rocks cover about three- quarters of the land surface For more about sedimentary rocks: For more about sedimentary rocks:

There are two kinds of weathering. There are two kinds of weathering. 1. Mechanical weathering 1. Mechanical weathering Disintegration, Physical Disintegration, Physical - breaks rocks into smaller and smaller pieces. It does not change the chemicals of the rocks. - breaks rocks into smaller and smaller pieces. It does not change the chemicals of the rocks. 2. Chemical weathering 2. Chemical weathering Decomposition Decomposition - also breaks rocks into smaller pieces. It changes the chemicals of the rocks. - also breaks rocks into smaller pieces. It changes the chemicals of the rocks.

Weathering breaks rocks into smaller pieces. It does not carry away the fragments. Erosion carries the fragments away.

CHEMICAL WEATHERING (DECOMPOSITION) CHEMICAL WEATHERING (DECOMPOSITION) Chemical weathering breaks up rocks and changes the chemicals of the rocks. Chemical weathering breaks up rocks and changes the chemicals of the rocks. Most chemical weathering is caused by the actions of oxygen, rain water, or carbon dioxide. Most chemical weathering is caused by the actions of oxygen, rain water, or carbon dioxide.

1. Oxygen in the air links up with some of the elements in rocks. The link-up forms oxides. The oxides break away from the rocks. 1. Oxygen in the air links up with some of the elements in rocks. The link-up forms oxides. The oxides break away from the rocks. One oxide that you know is rust. One oxide that you know is rust. 2. Rain water can change minerals in two ways. A) It dissolves some minerals. B) Water links up with other minerals. 2. Rain water can change minerals in two ways. A) It dissolves some minerals. B) Water links up with other minerals. 3. Carbon dioxide in the air dissolves easily in rain water. This forms carbonic acid. Acids dissolve limestone. 3. Carbon dioxide in the air dissolves easily in rain water. This forms carbonic acid. Acids dissolve limestone.

Plant Wedging

Limestone cave features chemical weathering

Streams and Erosion

Glacier Erosion

Mechanical Weathering or Disintegration or Physical Weathering

There are four main causes: 1. Temperature Change 2. Frost Action 3. Root Action 4. Animal Activity

Water Erosion

Root Growth

Oxidation