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Rocks
Chapter 4 in Orange Glencoe Book
• Rocks
• Minerals
• Elements
Chapter 4, Section1
Rock: a mixture of minerals, volcanic
glass, organic matter or other materials.
–
Display the physical and chemical
properties of the minerals that make them
up.
– Now, could organic materials be rocks?
Rock Cycle shows us that rocks
constantly, yet slowly, change into
different types. Page 91.
 Matter can never be created or destroyed,
only changed
 (Law of Conservation of Matter)
Rock Cycle
James Hutton – 1788
Must memorize the Rocks, Stages and Processes SOON!
• Insert Picture Here
What process forms:
1. Igneous rocks?
Melting * and Cooling
2. Sedimentary rocks?
Weathering, Erosion, * Compaction
and Cementation
3. Metamorphic rocks?
Heat and Pressure
Let’s Review:
 What is the model called that shows how rocks
constantly, yet slowly, change into different types
– The Rock Cycle (Page 91)
 Is there a definite pattern that the rock cycle
follows? Name some.
– BTW, My fav. Is S,I,I,M,S,I,I,S
 Who recognized/discovered the rock cycle? When?
– James Hutton – 1788 - “The founder of modern geology”
 What are the three types of rocks?
– Igneous, Sedimentary, Metamorphic
 What are the processes that form each type of rock?
– Igneous?Metamorphic?
Sedimentary?
Chapter 4, Section 2: Igneous rocks
Form by lava or magma cooling
– Both are melted rock, so what is the difference?
Two main types of igneous rocks:
– Intrusive - rocks formed slowly by magma
inside the Earth - large crystals (grains)
 Name one:
– Extrusive rocks formed quickly from lava
outside of the Earth - - smaller crystal (grains)
 Name one:
Earth’s Heat
• The heat that produces magma comes from the
radioactive decay of elements in the core of the
Earth!!!
Crystal Size? Name a rock for each.
Extrusive vs. Intrusive
Magma versus
lava:
`




Found where:
Cools how fast:
Crystal size:
Forms what kind of igneous rock:
Three types of igneous rocks: based on
the type of magma/lava
– Basaltic:
 Dense and dark colored
 High in Iron and magnesium
– Andesitic
 Medium
– Granitic:
 Less dense and light colored
 High in Silicon and oxygen
• What elements in a basaltic and granitic
igneous rocks make the densities
different?
• Basaltic: High in Iron and Magnesium,
low in silicate minerals.
• Granitic: High in Oxygen and Silicon,
low in iron and magnesium.
• VERY important to understand the chart
on page 96!!!
Chart on p. 96 Questions – Be able to EXPLAIN
– very similar to your quiz – Ooops, did I say that?
– Which cooled faster? Diorite or Andesite?
– What do Granite and Rhyolite have in common?
– What makes them different?
– Would you expect Gabbro or Granite to be more
dense?
– Based only on color, how could you know that Pumice
is granitic and Scoria basaltic?
– What elements are probably in Basalt?
– NOW can you Friday’s question of which is more dense,
basalt or granite? Remember that later this year.
Chapter 4 Section 3
Metamorphic rocks
Meta – Greek for “form”; Morph – “to change”
Rocks that are changed by:
1. heat and pressure (but were never melted)
2. the presence of hot fluids.
Metamorphic rocks form from already existing Sed.,
Ig. or Met. rocks.
The preexisting rock is called the
parent rock.
• Insert Pic of heated fluid
Metamorphic rocks come in two types:
examples on page 101-102.
• Foliated (layered or banded) like slate and gneiss
• Nonfoliated (no layers or bands) like marble or
quartzite
Gneiss
Parent rock was granite.
Marble
Parent rock was Limestone.
Quartzite
Parent rock was Sandstone.
Slate
Parent rock was Shale.
Schist
• Foliated rock that also forms from shale
– Huh? I though shale became slate, Mr.
Hayden?
Chapter 4, Section 2 Review
• What makes a metamorphic rock? (two things)
• Name a foliated rock, describe its appearance and
its parent rock.
• Name a nonfoliated rock, describe its appearance
and its parent rock.
Chapter 4, Section 4
Sedimentary rocks
• Most likely to contain fossils and
organic material. Why?
• Sedimentary rocks are broken
down into three types.
1. Detrital Sedimentary Rocks
(Clastic)
• These rocks are made of previously
existing rocks.
• The process that creates detrital
sedimentary rocks is weathering, erosion,
compaction, cementation
– Order important!!!
• Examples include shale, siltstone,
sandstone, conglomerate
• Named based on the sediment SIZE. (105)
Detrital Rock Classification
The Sediment Size in rocks tells about the environment
they were deposited, and the velocity of the water that
deposited them.
Sandstone – beaches or deserts
Shale - deep, calm water
Limestone - very deep ocean water
Conglomerate – rivers (mixed velocities)
Stacked rocks
• Law of Superposition
• In an undisturbed
layer of stacked rocks,
the oldest rocks are
found at the bottom
and youngest at top.
2. Organic Sedimentary Rocks
• Organic rocks are made of once-living
things
– Examples of once living things are shells, dead
plants, etc.
• Examples of organic rocks are:
• Coal
• Chalk
• Coquina
3. Chemical Sedimentary Rocks
• Formed from dissolved minerals in
solution
• Examples include limestone (contains
CaCO3) and rock salt
Very important review:
List Example of Each and which of the
three types
Organic
Foliated
Chemical:
Intrusive
Basaltic
Nonfoliated
Granitic:
Detrital:
Extrusive