Rocks Table of Contents Classifying Rocks Igneous Rocks

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Rocks Table of Contents Classifying Rocks Igneous Rocks Sedimentary Rocks from Reefs Metamorphic Rocks

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

Rocks - Classifying Rocks • When studying a rock sample, geologists observe the rock’s

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

Rocks - Classifying Rocks Mineral Composition and Color • Rock – a solid mixture

Rocks - Classifying 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. • Color can sometimes help determine composition – 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

Rocks - Classifying Rocks Texture • Grains – particles of minerals or other rocks

Rocks - Classifying 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. • Scientists look at the size, shape, and pattern of the grains to determine the texture.

Rocks - Classifying Rocks Texture • Grain size – Coarse-grained – large easy to

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

Rocks - Classifying Rocks Texture • Grain Shape – varies greatly from sand grains

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

Rocks - Classifying Rocks How Rocks Form • Geologists classify rocks into three major

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

Rocks - Classifying Rocks How Rocks Form • Igneous rock – type of rock

Rocks - Classifying Rocks How Rocks Form • Igneous rock – type of rock that forms from the 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, pressure, or chemical reactions.

Rocks - Igneous Rocks Classifying Igneous Rocks • Igneous rocks are classified according to

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

Rocks Classifying Igneous Rocks • Extrusive igneous rock – forms from lava on Earth’s

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 finergrained rock than intrusive igneous rock • People throughout history have used igneous rock for tools and building materials.

Rocks - Igneous Rocks Mineral Mixture • Granite is a mixture of light-colored minerals,

Rocks - Igneous 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.

Rocks - Igneous Rocks Mineral Mixture • Reading Graphs: – What mineral is most

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

Rocks - Igneous Rocks Mineral Mixture • Reading Graphs: – About what percentage of

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

Rocks - Igneous Rocks Mineral Mixture • Calculating: – If the amount of quartz

Rocks - Igneous Rocks Mineral Mixture • 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? – 100% - (35% + 10%) = 55%

Rocks - Igneous Rocks Mineral Mixture • Predicting: – How would the color of

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

Rocks - Igneous Rocks Links on Igneous Rocks • Click the Sci. Links button

Rocks - Igneous Rocks Links on Igneous Rocks • Click the Sci. Links button for links on igneous rocks.

Rocks - Sedimentary Rocks From Sediment to Rock • Most sedimentary rocks are formed

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

Rocks - Sedimentary Rocks From Sediment to Rock • Sediment – small, solid pieces

Rocks - Sedimentary 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.

Rocks - Sedimentary Rocks From Sediment to Rock • Compaction – process by which

Rocks - Sedimentary 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

Rocks - Sedimentary Rocks Types of Sedimentary Rock • There are three major groups

Rocks - Sedimentary 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

Rocks - Sedimentary Rocks Types of Sedimentary Rock • Organic rock – sedimentary rock

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

Rocks - Sedimentary Rocks Types of Sedimentary Rock • Chemical rock – sedimentary rock

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

Rocks - Sedimentary Rocks Uses of Sedimentary Rock • Sedimentary rock has been used

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

Rocks - Sedimentary Rocks Links on Sedimentary Rocks • Click the Sci. Links button

Rocks - Sedimentary Rocks Links on Sedimentary Rocks • Click the Sci. Links button for links on sedimentary rocks.

Rocks - Rocks From Reefs Coral Reefs • Coral reef – a structure of

Rocks - Rocks From Reefs 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 - Rocks From Reefs More on Coral Landforms • Click the PHSchool. com

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

Rocks - Metamorphic Rocks Metamorphic Rock • Metamorphic rock – forms when heat and

Rocks - Metamorphic 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.

Rocks - Metamorphic Rocks Types of Metamorphic Rocks • Geologists classify metamorphic rocks according

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

Rocks - Metamorphic Rocks Types of Metamorphic Rocks • Nonfoliated rocks – metamorphic rocks

Rocks - Metamorphic 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

Rocks - Metamorphic Rocks Links on Metamorphic Rocks • Click the Sci. Links button

Rocks - Metamorphic Rocks Links on Metamorphic Rocks • Click the Sci. Links button for links on metamorphic rocks.

Rocks - The Rock Cycle A Cycle of Many Pathways • Forces deep inside

Rocks - The Rock Cycle 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.

Rocks - The Rock Cycle • Rock cycle – processes on the surface and

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

Rocks - The Rock Cycle and Plate Tectonics • Plate movements start the rock

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.

Rocks - The Rock Cycle Activity • Click the Active Art button to open

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

Rocks - The Rock Cycle Metamorphic Sedimentary Igneous

Rocks - The Rock Cycle Metamorphic Sedimentary Igneous

Rocks Graphic Organizer Metamorphic Igneous Extrusive Organic Chemical Foliated

Rocks Graphic Organizer Metamorphic Igneous Extrusive Organic Chemical Foliated