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Rocks Classifying Rocks Igneous Rocks Sedimentary Rocks Rocks from Reefs Metamorphic Rocks The Rock Cycle Table of Contents.

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Presentation on theme: "Rocks Classifying Rocks Igneous Rocks Sedimentary Rocks Rocks from Reefs Metamorphic Rocks The Rock Cycle Table of Contents."— Presentation transcript:

1 Rocks Classifying Rocks Igneous Rocks Sedimentary Rocks Rocks from Reefs Metamorphic Rocks The Rock Cycle Table of Contents

2 Rocks When studying a rock sample, geologists observe the rock’s mineral composition, color, and texture. Studying Rocks - Classifying Rocks

3 Rocks Mineral Composition and Color Rock – a solid mixture of minerals and other materials. Rock-forming minerals – the common minerals that make up most of the rocks of Earth’s crust. –Granite – tends to be a light-colored rock that has high silica content –Basalt – tends to be a dark-colored rock that is low in silica - Classifying Rocks

4 Rocks Texture Grains – particles of minerals or other rocks that give a rock its texture. Texture – the look and feel of a rock’s surface, determined by the size, shape, and pattern of a rock’s grains. - Classifying Rocks

5 Rocks Texture Grain size –Coarse-grained – large easy to see grains –Fine-grained – so small they can only be seen under a microscope - Classifying Rocks

6 Rocks Texture Grain Shape – varies greatly from sand grains to large triangular grains Grain Pattern – can vary also from layers to swirls to bands - Classifying Rocks

7 Rocks How Rocks Form Geologists classify rocks into three major groups: –igneous rock, sedimentary rock, and metamorphic rock. - Classifying Rocks

8 Rocks How Rocks Form Igneous rock – type of rock that forms from the melting then cooling of molten rock at or below the surface. Sedimentary rock – type of rock that forms when particles from other rocks or the remains of plants and animals are pressed and cemented together. Metamorphic rock – type of rock that forms from an existing rock that is changed by heat and pressure - Classifying Rocks

9 Rocks Classifying Igneous Rocks Igneous rocks are classified according to their origin, texture, and mineral composition. - Igneous Rocks

10 Rocks Classifying Igneous Rocks Extrusive igneous rock – forms from lava on Earth’s surface. Intrusive igneous rock – forms when magma hardens beneath Earth’s surface. The faster igneous rock cools, the finer the grains –Extrusive igneous rock tends to be a finer- grained rock than intrusive igneous rock

11 Rocks Mineral Mixture Granite is a mixture of light-colored minerals, such as feldspar and quartz, and dark-colored minerals, including hornblende and different types of mica. But granite can vary in mineral composition. This affects its color and texture. - Igneous Rocks

12 Rocks Mineral Mixture –Feldspar Reading Graphs: –What mineral is most abundant in granite? - Igneous Rocks

13 Rocks Mineral Mixture –10% Reading Graphs: –About what percentage of granite is made up of dark minerals? - Igneous Rocks

14 Rocks Mineral Mixture –100% - (35% + 10%) = 55% Calculating: –If the amount of quartz increases to 35 percent and the amount of dark-colored minerals stays the same, what percentage of the granite will be made up of feldspar? - Igneous Rocks

15 Rocks Mineral Mixture –The overall color would be darker. Predicting: –How would the color of the granite change if it contained less feldspar and more mica and hornblende? - Igneous Rocks

16 Rocks Links on Igneous Rocks Click the SciLinks button for links on igneous rocks. - Igneous Rocks

17 Rocks From Sediment to Rock Most sedimentary rocks are formed through a series of processes: erosion, deposition, compaction, and cementation. - Sedimentary Rocks

18 Rocks From Sediment to Rock Sediment – small, solid pieces of material that come from rocks or organisms. –Usually forms due to erosion Erosion – a destructive process in which water or wind loosens and carries away fragments of rock. Deposition – process by which sediment settles out of the water or wind that is carrying it. - Sedimentary Rocks

19 Rocks From Sediment to Rock Compaction – process by which sediments are pressed together under their own weight. –Occurs over millions of years as layers build Cementation – process by which dissolved minerals crystallize and glue particles of sediment together into one mass. –Takes place when sediment is in the presence of water - Sedimentary Rocks

20 Rocks Types of Sedimentary Rock There are three major groups of sedimentary rocks: –clastic rocks, organic rocks, and chemical rocks. Clastic rock – sedimentary rock that forms when rock fragments are squeezed together under high pressure. –Can range in size from microscopic clay particles to large boulders –Ex: shale, sandstone, conglomerate, and breccia - Sedimentary Rocks

21 Rocks Types of Sedimentary Rock Organic rock – sedimentary rock that forms from remains of organisms deposited in thick layers. –Ex: Coal and Limestone –Coal forms from the remains of swamp plants buried in water. –Limestone forms in the ocean, where many living things, such as coral, clams, and oysters, have hard shells made of calcite that collect on the ocean floor. - Sedimentary Rocks Peat Bituminous Lignite Anthracite

22 Rocks Types of Sedimentary Rock Chemical rock – sedimentary rock that forms when minerals crystallize from a solution. (Reacts to HCl) –Ex: Limestone forms from calcite deposits dissolved in lakes, rivers, streams. - Sedimentary Rocks

23 Rocks Uses of Sedimentary Rock Sedimentary rock has been used for thousands of years in building structures, tools, and statues. –Ex: The White House in Washington D.C. is constructed of sandstone. - Sedimentary Rocks

24 Rocks Links on Sedimentary Rocks Click the SciLinks button for links on sedimentary rocks. - Sedimentary Rocks

25 Rocks Coral Reefs Coral reef – a structure of calcite skeletons built up by coral animals in warm, shallow ocean water. –When coral animals die, their skeletons remain. More corals build on top of them, gradually forming a coral reef. –Only form in ocean water between 30°N and 30°S latitude - Rocks From Reefs

26 Rocks Coral Reefs(not in notes) Coral reef is really organic(from living things) limestone. Deposits of organic limestone help geologists figure out what the environment was like long ago. If they find a fossil of coral reef, they would know that location used to contain warm, shallow ocean water.

27 Rocks More on Coral Landforms Click the PHSchool.com button for an activity about coral landforms. - Rocks From Reefs

28 Rocks Metamorphic Rock Metamorphic rock – forms when heat and pressure beneath Earth’s surface changes the appearance, texture, crystal structure, and mineral content of either igneous, sedimentary, or other metamorphic rock. - Metamorphic Rocks

29 Rocks Types of Metamorphic Rocks Geologists classify metamorphic rocks according to the arrangement of the grains that make up the rocks. –Foliated rocks – metamorphic rocks that have grains arranged in parallel layers or bands. –Ex: Slate – metamorphic shale (denser and more compact than shale) - Metamorphic Rocks Shale Slate Gneiss

30 Rocks Types of Metamorphic Rocks Nonfoliated rocks – metamorphic rocks that have randomly arranged metamorphic grains that do not split into layers –Ex: Quartzite – metamorphic sandstone Marble – metamorphic limestone - Metamorphic Rocks

31 Rocks Links on Metamorphic Rocks Click the SciLinks button for links on metamorphic rocks. - Metamorphic Rocks

32 Rocks A Cycle of Many Pathways Forces deep inside Earth and at the surface produce a slow cycle that builds, destroys, and changes the rocks in the crust. - The Rock Cycle

33 Rocks Rock cycle – processes on the surface and inside Earth that slowly change rocks from one kind to another. - The Rock Cycle

34 Rocks The Rock Cycle and Plate Tectonics Plate movements start the rock cycle by helping to form magma, the source of igneous rocks. Plate movements also cause faulting, folding, and other motions of the crust that help to form sedimentary and metamorphic rocks. - The Rock Cycle

35 Rocks Rock Cycle Activity Click the Active Art button to open a browser window and access Active Art about the rock cycle. - The Rock Cycle

36 Rocks Igneous Sedimentary Metamorphic - The Rock Cycle

37 Rocks Graphic Organizer Igneous Metamorphic Extrusive Organic Chemical Foliated


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