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ROCKS, ROCKS, AND MORE ROCKS! Chapters 5 and 6 (Glencoe Earth Science)

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Presentation on theme: "ROCKS, ROCKS, AND MORE ROCKS! Chapters 5 and 6 (Glencoe Earth Science)"— Presentation transcript:

1 ROCKS, ROCKS, AND MORE ROCKS! Chapters 5 and 6 (Glencoe Earth Science)

2 What is a rock?  A rock is a hard substance made of one or more minerals  There are 3 types of rocks:  Igneous  Sedimentary  Metamorphic

3 What’s an Igneous Rock?  Formed by crystallization of magma  Igneous comes from the latin word for fire  These rocks are associated with fiery lava flows  Lava is magma that flows on the Earth’s surface

4 Types of Igneous Rocks  Extrusive  Formed from lava on Earth’s surface that cooled quickly  Known as volcanic rock  Fine-grained  Intrusive  Formed inside the Earth  Magma rises up into pre-existing rocks and hardens  Coarse-grained  Called “Plutonic” rocks after Pluto, the god of the Underworld  These rocks commonly produce landforms  Granite is most common

5 Igneous Rocks  Which is the intrusive rock?  Which is the extrusive rock?

6 What About Igneous Rocks?  Useful as building materials  Interlocking grainy texture provides strength  Resistant to weathering  Granite is especially durable Used for columns, tiles and countertops, etc.  Valuable ore deposits are often associated with igneous rocks

7 It’s Sedimentary, Watson!  What’s a sedimentary rock?  A rock formed from sediments  Sediments are pieces of material that have been carried/deposited by wind, water, etc.  Sedimentary rocks form when these pieces are cemented together

8 How do Sedimentary Rocks Form?  Weathering  Processes that break rock into smaller pieces Chemical-minerals in rock are dissolved or chemically changed Physical-minerals are unchanged; rock fragments break off  Erosion  Movement of materials from one location to another Caused by wind, moving water, gravity, glaciers (ice) Eroded materials almost always moved downhill

9 Sediments, Classified  Clastic Rock  Refers to fragments of rock and minerals created by weathering and erosion  Clastic comes from the Greek word for “broken”  Classified by particle size

10 Deposition  Occurs when sediments are laid down on the ground or sink to the bottom of a body of water  When wind/water slows down, largest particles settle out first, etc. Smallest particles settle last.  Sediments moved by glaciers and landslides are not sorted.

11 Burial  Most sediments are deposited in basins (depressions)  As more sediments are deposited, the layers on the bottom are exposed to more heat and pressure.  Causes lithification  Physical and chemical processes that turn sediment into sedimentary rock

12 Process of Lithification  1-Compaction  Weight of sediments forces them closer together  Water is squeezed out of mud  Sand resists compaction because of grain-to-grain contact

13 Process of Lithification  2-Cementation  Temperatures increase  Buried sediments can be chemically changed  Mineral growth cements sediments together into solid rock Two types of cementation A new mineral grows between grains OR The same mineral grows between or over grains

14 Features of Sedimentary Rock  Horizontal layering (bedding)  Graded bedding: particle size becomes more coarse/heavy toward bottom layers  Cross-bedding: formed as inclined layers of sediment move forward across a horizontal surface  Fossils  Evidence of once-living organisms

15 Types of Sedimentary Rock  Clastic Rock  Most common; formed from deposits of loose sediments  1/3 or more is pebble-called conglomerate Not as common as rock w/ smaller pieces  If made with sandy grains-called sandstones Very common  Particles smaller than sand-called shale

16 Types of Sedimentary Rock  Chemical Rocks  Formed when water evaporates leaving minerals behind  Ex: Rock salt, some limestone Stalactites, stalagmites  Organic Sedimentary Rocks  Formed from remains of a once-living thing  Ex: coal

17 Why are Sedimentary Rocks Important?  Energy Resources  Coal, Oil, Natural gas are found in sedimentary rock  Many metals are mined from sedimentary rocks  Used in making cement (limestone)  Used in making blocks for walls (sandstone, limestone)

18 Metamorphic Rock  Changing one type of rock into another as a result of extreme heat, pressure, and/or chemical reactions  Can be formed from any of the three types of rock  The ‘new’ rocks have different properties than the rock did before the ‘morph’

19 The Rock Cycle  Continuous changing and remaking of rocks  Rocks are constantly being recycled from one type to another

20 Example of the Path of a Rock Through the Rock Cycle  Granite (igneous rock)  Wind/rain erodes exposed rock, bits flake off, carried to bottom of stream  carried to river, along with other sediments  carried to sea, deposited  Deposits build up  form sandstone (sedimentary rock)   Sediments continue to be buried and are under more pressure/higher temps  pressed together even more  form quartzite (metamorphic rock)  AND THE CYCLE CONTINUES…

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