Download Rocks - Warnick

RAP 12/17
pg 94
1. What is a rock?
2. What are the three types of rocks?
Topic: Rocks —Chapter 6
6.1 How Rocks Form
6.2 Igneous Rocks
6.3 Sedimentary Rocks
6.4 Metamorphic Rocks
How Rocks Form

In this section, we will be answering two
questions:
• What is a rock?
• What is the rock cycle?
?
What is a rock?
=group of minerals bound together.
A. Rock Cycle
link
Rock Cycle Diagram

Tape the Rock Cycle onto page 95 in
your notebook.
Rocks!
Metamorphic
Sedimentary
Igneous
B. Rock Types
1. Igneous Rocks
a. form from crystallization of magma
_____
b. Classification
i. Type of magma
-Felsic or Granitic or Rhyolitic-rocks are
light colored and have high silica content
- Mafic rocks are dark colored, have
lower silica
Felsic or Mafic?
Mafic
________
http://www.pitt.edu/~cejones/GeoImages/2IgneousRocks/IgneousCom
positions/7Rhyolite/RhyoliteCUp.jpg
Felsic
________
http://itc.gsw.edu/faculty/tweiland/gabbro.jpg
RAP
12/18 (pg 96)
1. The rock shown is composed primarily of
large crystals that were formed by
a. Cooling magma
b. Compacting shells
c. weathering
d. faulting
2. What word would describe the type of
magma that formed this rock?
3. Why?
Classifying Igneous Rocks
ii. Grain size or texture
- Extrusive rocks are fine-grained.
- Intrusive rocks are coarse-grained
http://core.ecu.edu/geology/harper/igneous/I15lg.gif
Classifying Igneous Rocks
• two types:
Extrusive
-______________-lava
cools
quickly on Earth’s surface, small
crystals (fine-grained)
Intrusive
-________________-lava cools
slowly underground, large crystals
(coarse-grained)
Intrusive or Extrusive?
___________________
________________
volcano.und.nodak.edu/.../volcanic_rocks.html
http://cc.usu.edu/~sharohl/glossary.html
1. What are the two main ways petrologists
classify igneous rocks?
2. If you find a rock that is dark with large
grains, what 2 terms would you use to
describe it?
3. If you find a light rock with large crystals,
what 2 terms would you use to describe
it?
4. If you find a light rock with small crystals,
what 2 terms would you use to describe
it?
RAP 1/2 pg. 96
Welcome Back!
1. What two processes would occur to
change a metamorphic rock to an
IGNEOUS rock?
2.
RAP 1/3 pg. 96
1. How do metamorphic rocks form?
2. What two ways are metamorphic rocks
classified? (hint-use your essentials)
2. Metamorphic
heat
a. changed by ___________
and
pressure
___________
Types of metamorphism
1. Regional
2. Contact
3. Hydrothermal
1. Regional Metamorphism
•affects large regions
of the Earth’s crust
•most often generated
by the compressive
forces of mountain
building
www.gly.fsu.edu/.../ 7_Rocks/7_Rocks_index.htm
2. Contact
Metamorphism
•occurs when solid rock
comes in contact with
molten rock solid rock,
igneous
usually from an ________
intrusion.
http://enterprise.cc.uakron.edu/geology/natscigeo/
Lectures/smrocks/metafig.gif
3. Hydrothermal
Metamorphism
•occurs when very hot
water reacts with
rock.
http://www.uoguelph.ca/~sadura/metref/met19.gif
Places where metamorphic rocks
can form.
Formation of metamorphic rocks
Pressure from the weight
of overlying rocks
b. Textures
i. Foliated
ii. Nonfoliated
i. Foliated
• foliated : wavy layers and bands of minerals
• high pressure during metamorphism, can cause
flat or needle-like crystals to form
Gneiss
Ex_________:
alternating
bands of light
and dark
Gneiss Rocks!
Photo courtesy of Claude G. Genest, University of Quebec
at http://www.uqtr.uquebec.ca/relief/Terme/Photo/IMG0054.jpg
Gneiss
Gneiss
Mineral Changes During Foliation
,
Diagram courtesy of Dr. Jürgen Schieber Indiana University, at
http://www.indiana.edu/~geol105/images/gaia_chapter_5/foliation.jpg
Foliation: Slate
Photo courtesy of David L. Ozsvath, University of Wisconsin, at
http://www.uwsp.edu/geo/faculty/ozsvath/images/slate.jpg
You don’t know schist!
Granite schist with garnet porphyroblasts
http://www.otago.ac.nz/geology/features/rocks-minerals/schist-gnt.jpg
Schist happens!
http://www.gc.maricopa.edu/earthsci/imagearchive/DK_MICA_SCHIST_big.jpg
ii. Nonfoliated
-Blocky crystal shapes
Example: Quartzite
http://www.physci.wsc.ma.edu/young/pgeol/g
eoinfo/images/rocks/quartzite.jpg
Shale
Slate
Phyllite
Schist
Parent rocks and their
metamorphic babies.
Do Now
12/17
Using the chart above:
1. Rocks subjected to high temperature and
pressure during metamorphism, can form ______.
2. What are two possible parent rocks of gneiss?
3. What does limestone turn into when it undergoes
metamorphism?
Metamorphic Mini lab
RAP 1/4 pg. 98
1. Schist is a type of _______ metamorphic rock.
2. Marble is a type of ______ metamorphic rock.
3. Granite is a type of _______ igneous rock.
4. Pumice is a type of ______ igneous rock.
3. Sedimentary Rocks
a.formed from sediments,
dissolved minerals, and/or
organic materials
b. Process of formation:
i. Weathering
-the breaking down of
rock into smaller
pieces by physical
and chemical
processes
ii. Erosion
-the movement of
sediments
iii. Lithification- process of
turning sediments into rock
- compaction of
sediments by
overlying layers
squeezed out
excess space and
water
and
cementation occurs
as dissolved
minerals cement
sediment grains
together
c. Types of Sedimentary Rock
1. Clastic
2. Nonclastic
i. Clastic
-formed from fragments of other rocks or
organic material
- classified by size and shape of fragments
Sediment
Gravel
Sand
Silt
Clay
Size
2mm
0.063 – 2mm
0.004 – 0.063mm
<0.004mm
Rock Example
Conglomerate or
breccia
Sandstone
Siltstone
Shale
Clastic Formation Animation
• http://www.classzone.com/books/earth_sci
ence/terc/content/visualizations/es0605/es
0605page01.cfm?chapter_no=visualizatio
n
ii. Nonclastic
-form from dissolved minerals coming out of
solution by precipitation or evaporation
-fine-grained unless they are crystallized
Limestone (chalk)
Precipitated Mineral: Death Valley
RAP 1/7 pg. 98
1. What are the two types of sedimentary
rocks?
2. A rock made of pieces of sand would be
which type of sedimentary rock?
By the end of class I will…
1. Be able to use sedimentary, metamorphic
and igneous features to describe past
environments.
2. Be able to sort rocks into their rock type
based on their characteristics.
Tuff
• One other by-product of a volcano is tuff.
– Tuff is formed when volcanic ash from a
volcano is buried and compressed.
Rock Features
A. Igneous
i. Dike
– A dike is a sheet of igneous rock that cuts
across rock layers vertically at a steep
angle.
– A dike forms when magma intrudes into
angled cracks.
– A dike can be hundreds of kilometers long,
and anywhere from a centimeters to many
meters thick.
Igneous Formations
ii. Sill
– A sill is a sheet of igneous rock that lies
parallel to the layers it intrudes.
– A sill is formed when magma is forced
between, not across, rock layers.
– A sill can be hundreds of meters thick, and
many kilometers long.
Sill
iii. Batholiths
-large mass of rock that form the core of
many mountain ranges.
• Batholiths are usually made of granite.
• Batholiths are exposed through the uplift
and erosion of overlying rock layers.
Batholith
Igneous Formations
• Laccoliths
– A laccolith occurs when magma bulges
upward to form a dome
Laccoliths
Igneous Formations
• Volcanic Neck
– A volcanic neck is left after an inactive
volcano erodes
– A volcanic neck is the central plug of
hardened magma
Volcanic Neck
What formations do you see?
3
4
1
2
6
5
Sedimentary Features!
*** Sedimentary rocks often have evidence of
past life, or
.
Fossils!!!
http://alpha.dickinson.edu/departments/geol/rennie/fish_2.jpg
Importance of Sedimentary Rocks
1. Sedimentary rocks are important for
reconstructing Earth’s past life and climatic
conditions.
2. Sedimentary rocks contain valuable resources
such as petroleum, coal, iron, uranium, and others.
Sedimentary Features!
a. Horizontal layering called bedding
–
Two types of bedding include:
1. Graded bedding
2. Cross-bedding
Sedimentary Features!
Type 1.Graded bedding :
contains
progressively
coarser sediments
toward the bottom
layers
Sedimentary Features!
Type 2.–
Cross-bedding:
contains inclined
layers of sediment
moving forward
against a
horizontal surface
http://faculty.uaeu.ac.ae/~afarrag/physical%20geology/cross%20beddi
ng%20copy.jpg
Ripple Marks with
embedded halite crystals.
Mudcracks found in
Death Valley.
www.geosci.unc.edu/.../ SedStructures.html
RAP 1/8 pg. 98
1. What is the difference between a dike
and a sill?
2. What underlies the Blue Ridge
Mountains?
By the end of class, I will …
1. Show what I know on my rocks quiz
2. List rock types of each Virginia province
using a geologic map and describe how
plate tectonics helped form these rocks
Rocks in Virginia
RAP
1/9
pg 98
1. Extrusive rocks have small grains because they a. harden underground.
c. contain rare minerals.
b. have a rough mixture.
d. cool quickly.
2. Metamorphic rocks result from the
a.
b.
c.
d.
erosion of rocks
recrystallization of rocks
cooling and solidification of molten magma
compression and cementation of soil particles
3. Lava that cools quickly forms _____ rocks.
a. extrusive metamorphic
b. extrusive igneous
c. intrusive metamorphic
d. intrusive igneous