Earth Systems 3209
Unit: 3
Earth’s Materials
Reference:
Chapters 2, 3, 6, 7; Appendix A & B
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Unit 3:
Topic 2.1
Rocks and the Rock Cycle
Focus on . . .
 defining rock and recognizing the connection
between minerals and rocks.
 the rock cycle diagram and explaining the origin
of the three rock types.
 explaining the different processes that link each
rock type to the others (represented by arrows).
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Rocks and the Rock Cycle
What is a Rock?

A rock is a consolidated mixture of one or more minerals.

Rocks are generally composed of more than one mineral.
For example, Granite consist of;
Quartz, Feldspar, Hornblende and Mica.
Orthoclase
Feldspar
Quartz
Amphibole
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Rocks and the Rock Cycle
 Three Rock Types
1) Igneous Rocks
2) Sedimentary Rocks
3) Metamorphic Rocks
Text Reference:
pages 15-17
 All rock types are interrelated
through the rock cycle.
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Rocks and the Rock Cycle
Some common rocks include;
Igneous:
Granite, Gabbro, Diorite, Rhyolite, Basalt, Andesite,
Obsidian, Pumice, and Scoria.
Sedimentary:
Conglomerate, Breccia, Sandstone, Siltstone, Shale, and
Limestone.
Metamorphic:
Slate, Phyllite, Schist, Gneiss, Marble and Quartzite.
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Igneous Rocks
 Formed by the cooling and hardening of hot molten rock.
 If the molten rock is located within Earth it is called
Magma.
 If the molten rock reaches the surface and exits through
volcanoes, it is then referred to as Lava.
 Two classifications of Igneous rock;
1) Plutonic (intrusive) – forms from magma.
2) Volcanic (extrusive) – forms from lava.
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Sedimentary Rocks
 Rock formed when the weathered products of pre-existing
rocks have been transported, deposited, and compacted or
cemented into solid rock.
 Usually formed in marine (water) environments where
sediment is deposited by streams and rivers.
 Most of Earth’s crust (95%) is igneous rock but the surface is
covered by sedimentary rocks.
 Three classifications of Sedimentary Rocks:
1) Clastic (Detrital) – rock fragments
2) Chemical - precipitation and evaporation
3) Biochemical – organic remains
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Metamorphic Rocks
 Rock formed below Earth’s surface when preexisting rock is altered by heat, pressure, and
chemically active fluids.
 Metamorphism changes rocks in size, shape,
texture, and the minerals they contain.
 Metamorphism varies in degree from:
1) High Grade. Ex. Granite changes to Gneiss.
2) Low Grade.
Ex. Shale changes to Slate.
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Rock Cycle
Melting
Cool &
Crystallize
Igneous
(Volcanic)
(Plutonic)
Weathering &
Erosion
Magma
Metamorphic
Sedimentary
(Clastic)
(Chemical)
(Organic)
Heat &
Pressure
Compaction &
Cementing
Sediment
Sand, Silt, & Clay
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Rock Cycle
Magma
Cool &
Crystallize
Melting
Melting
Metamorphic
Igneous
(Volcanic)
(Plutonic)
Heat & Pressure
Heat &
Pressure
Sedimentary
(Clastic)
(Chemical)
(Organic)
Weathering &
Erosion
Weathering &
Erosion
Compaction &
Cementing
Weathering &
Erosion
Sediment
Sand, Silt, & Clay
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Example 1:
Which statement is true about the rock cycle?
(A) magma cools and crystallizes to form metamorphic rocks
(B) metamorphic rocks lithify to form sediments
(C) sedimentary rocks may contain igneous and metamorphic rocks
(D) weathering affects only igneous rocks
What rock forms when a pre-existing rock is altered as a result
of heat and pressure?
(A) Igneous
(B) Metamorphic
(C) Sandstone
(D) Sedimentary
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Example 2:
Which is a consolidated mixture of minerals?
(A) compounds
(B) elements
(C) fossils
(D) rocks
Which processes are responsible for the lithification
of sediments?
(A) cementation and compaction
(B) faulting and folding
(C) photosynthesis and respiration
(D) weathering and erosion
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Your Turn . . .
Take the time and complete the following questions . . .
In the diagram below, rock types/materials are indicated by numbers and
processes are indicated by letters. Indicate the rock types/materials and
processes for the rock cycle diagram by completing the table below.
A
1. Magma
E
2.
5.
Weathering &
Erosion
B
D
C
3.
4.
Rock Type / Materials
1.
Magma
Process
A
2.
B
3.
C
4.
D
5.
E
Weathering and Erosion
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Solutions . . .
In the diagram below, rock types/materials are indicated by numbers and
processes are indicated by letters. Indicate the rock types/materials and
processes for the rock cycle diagram by completing the table below.
A
Answer:
1. Magma
E
2.
5.
Weathering &
Erosion
B
D
C
3.
4.
Rock Type / Materials
Process
1.
Magma
A
Cool & Crystallize
2.
Igneous
B
Weathering and Erosion
3.
Sediments
C
Compacting & Cementing
4.
Sedimentary
D
Heat & Pressure
5.
Metamorphic
E
Melting
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Your Turn . . .
Take the time and complete the following questions . . .
(Solutions to follow)
Question:
In relation to the rock cycle, explain two processes
responsible for the formation of sedimentary rocks.
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Solutions . . .
Question:
In relation to the rock cycle, explain two processes responsible
for the formation of sedimentary rocks.
Lithification is the process that turns sediment into solid rock. This is
done through compaction and cementation.
Compaction occurs as the weight of the overlying material increases.
Compaction forces the grains closer together, reducing pore space and
eliminating some of the contained water.
Cementation occurs when water moving through pore spaces in
sediment may contain chemicals (silica/calcite) dissolved in solution.
These chemicals may precipitate as new minerals in the pore spaces.
This causes cementation, which will then start to stick the individual
particles together.
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Summary . . .
Overview of Points covered:
 3 Rock Types:
 Rock Cycle Includes:
Rock Type / Materials
Process
Magma
Cool & Crystallize
Igneous
Weathering and Erosion
Sediments
Compacting & Cementing
Sedimentary
Heat & Pressure
Metamorphic
Melting
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