Rocks Classifying Rocks Igneous Rocks Sedimentary Rocks Rocks from Reefs Metamorphic Rocks The Rock...
-
Upload
vicente-grubbe -
Category
Documents
-
view
270 -
download
5
Transcript of Rocks Classifying Rocks Igneous Rocks Sedimentary Rocks Rocks from Reefs Metamorphic Rocks The Rock...
Rocks
Classifying Rocks
Igneous Rocks
Sedimentary Rocks
Rocks from Reefs
Metamorphic Rocks
The Rock Cycle
Table of Contents
Rocks
• When studying a rock sample, geologists observe the rock’s mineral composition, color, and texture.
Studying Rocks- Classifying Rocks
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
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
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
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
Rocks
How Rocks Form• Geologists classify rocks into three major
groups: – igneous rock, sedimentary rock, and
metamorphic rock.
- Classifying Rocks
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
Rocks
Classifying Igneous Rocks• Igneous rocks are classified according to
their origin, texture, and mineral composition.
- Igneous Rocks
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
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
Rocks
Mineral Mixture
– Feldspar
• Reading Graphs:
– What mineral is most abundant in granite?
- Igneous Rocks
Rocks
Mineral Mixture
– 10%
• Reading Graphs:
– About what percentage of granite is made up of dark minerals?
- Igneous Rocks
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
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
Rocks
Links on Igneous Rocks
• Click the SciLinks button for links on igneous rocks.
- Igneous Rocks
Rocks
From Sediment to Rock• Most sedimentary rocks are formed
through a series of processes: erosion, deposition, compaction, and cementation.
- Sedimentary Rocks
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
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
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
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
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
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
Rocks
Links on Sedimentary Rocks
• Click the SciLinks button for links on sedimentary rocks.
- Sedimentary Rocks
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
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.
Rocks
More on Coral Landforms
• Click the PHSchool.com button for an activity
about coral landforms.
- Rocks From Reefs
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
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
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
Rocks
Links on Metamorphic Rocks
• Click the SciLinks button for links on metamorphic rocks.
- Metamorphic Rocks
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
Rocks
• Rock cycle – processes on the surface and inside Earth that slowly change rocks from one kind to another.
- The Rock Cycle
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
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
Rocks
Magma
Rock Cycle
Igneous
Sedimentary
Metamorphic
- The Rock Cycle
Rocks
Rocks
Sedimentary
includeinclude include
can be
IntrusiveNon-
foliatedClastic
Graphic Organizer
Igneous Metamorphic
Extrusive Organic Chemical Foliated