Download Rocks. - West Ada

Rocks.
• Geology
• Modern Geology is said to have
begun in 1795. James Hutton
• Uniformitari • “The present is the key to the past”
anism
• The geologic processes now at
work were also active in the past.
• And the present physical features
of Earth were formed by these
same processes at work over long
periods of time.
Three Groups of Rocks.
• Rock
3 classifications
of Rocks.
• A group of minerals bound
together in some way.
• Atoms, elements, molecules,
minerals, rocks.
• Igneous, Sedimentary, and
Metamorphic.
• All Classified by origin and
composition.
• Where they are formed and
what materials make them up.
• Igneous
• Sedimentary
• Metamorphic
• Rocks are formed by the cooling
and hardening of hot molten rock
from inside Earth.
• This hot molten rock is called
Magma.
• Rocks formed by the hardening
and cementing of layers of
sediments. Come from other
rocks.
• Are rocks that undergo a change
due to heat and pressure
underground.
Sedimentary Rocks
https://www.youtube.com/watch?v=sN7Afic
X9e0
Metamorphic rocks
Igneous rocks
Igneous Rocks
• Formation
• Plutonic
Rocks
• Igneous rock either forms at or
near the earth’s surface or deep
within the earth’s crust.
• Or intrusive Igneous rocks. Form
underground from cooling
magma. These rocks are seen
at the surface only when the over
lying rocks have been worn
away.
• Plutonic rocks develop larger crystal
structure because of their slow
cooling rate.
• Volcanic
Igneous
Rocks
•
Or extrusive rocks that form at or
near the surface
• Have a very fast cooling rates.
Crystal structure is very hard to see.
Volcanic
Plutonic
Identify these as either volcanic or
plutonic.
Magma and Lava Types.
• Magma
• Lava
• Two types:
• Molten rock underground.
• Molten rock at the earth’s
surface.
• Liquid rock that is thick and slow
flowing very high in the mineral
SILICA are called Felsic rocks.
• This type forms rocks like
Obsidian at the surface or
Granite under the surface. Forms
light colored rocks.
• Silica is the key ingredient.
• Mafic magma/lava is the second type.
Hotter, thinner and more fluid than felsic.
Produces dark colored rocks. It has a
low silica content. Forms rocks like
basalt at the surface.
• Textures-
• Igneous rocks are grouped also by their
textures. Or in other words the size
shape and arrangement of its mineral
crystals.
• Crystal size is the most important factor.
• This depends on how fast the magma
cools.
• Types of
textures
• Smooth grained texture: has no
visible crystals.
• Coarse Grained texture: Has visible
crystal.
• Glassy Texture. Has the appearance
of glass.
• Porferitic texture. Has two distinct
crystal sizes. Due to two cooling
rates.
• Note
• When rock is in the liquid state, its
atoms are free to move around and
arrange into crystals. The longer the
magma stays liquid the larger the
crystals.
• Magma has dissolved gas and the
more gas dissolved in the magma the
larger the crystals grow.
Smooth
Porferitic
Coarse
Glassy
Common Igneous rocks.
• Granite
• Coarse grained Igneous rock.
Common rock in the rocky mtns.
• Several types according to mineral
content.
• Visible crystals
• Composed of light colored
minerals, quartz, feldspar and
some hornblende.
The addition of various minerals like olivine makes granite different colors.
Basalt
• Basalt
• Most common igneous rock.
• Forms at or near the surface
by cooling lava and magma.
• Cools very quickly
• No visible crystals. Fine
grained rock.
• Often has vesicles. Holes or
voids in the rock where
volcanic gasses were trapped
by the solidifying material.
Rhyolite
• Rhyolite
• Composed of the same light
colored minerals as in granite.
• Cools at or near the surface very
quickly.
• Is fine-grained.
Obsidian
• Obsidian
• Dark colored igneous rock
however, has a composition
similar to Granite.
• Cools very quickly at the surface.
• Glassy texture.
• Had many uses for Native
Americans due to its unique way
of breaking.
#1 Igneous Topic Questions
1. Describe the difference between intrusive and extrusive
rocks.
2. Name & describe the FOUR types of rock textures.
3. Draw a detailed piece of granite (colored) & label the
minerals that compose it (page 95 red text).
Sedimentary Rocks
• Sedimentary
Rocks
• Rocks made of other rocks.
• Three types. Clastic, Organic
(Fossil) and Chemical.
• Although most of the Earth’s
crust is made of igneous rock,
most of its surface is covered
by sedimentary rocks.
• Clastic
Sedimentary
Rocks
• Examples
• Clasts are fragments of other
rocks that range in size from
boulders to silt and clay
particles.
• When clasts get stuck together
by natural cements like silica or
calcite they form clastic
sedimentary rocks.
• Shale, sandstone and
conglomerate.
Clastic
Sedimentary
Rocks
• Sedimentary rocks are formed
• Chemical
from mineral grains that fall out of
Sedimentary
a solution by evaporation or by
Rocks
chemical action.
• Rock salt and limestone are
examples of chemical
sedimentary rocks.
Lake drying in the sun. Water evaporates and
leaves the dissolved minerals behind creating
chemical sedimentary rocks.
• Organic
Sedimentary
Rocks
• Sedimentary Rocks are formed
from the remains of plants and
animals.
• Coal and limestone made of shell
fragments are also examples.
Fossils in Sedimentary Rocks
• Fossils
• Remains or impressions of plants
and animals preserved in a rock.
• Sedimentary rocks are the only
rock type that you will find fossils.
• As sediments pile up, animals and
plants that die in the area are
buried. The soft parts dissolve
away and decay. The hard parts
may remain as a fossil.
Sedimentary rock identification
• In your comp book label rocks 1-3 with an
“A” if you believe it is clastic, “B” if you
believe it is chemical and “C” if you believe
it is fossil. Answers may be used more
than once.
Sedimentary Review
1. What Rock type is the only one that will
contain fossils?
2. Name the three types/classes of
sedimentary rocks.
3. How do chemical sedimentary rocks
form?
4. How do clastic sedimentary rocks form?
Metamorphic Rock
• Formation
•All of the metamorphic rock are rocks that
undergo some type of change due to intense
heat and pressure.
•The type of pressure needed to change a
rock’s structure can only be achieved at great
depths in the earth’s crust.
• Two types
• Regional
•Regional and Contact Metamorphism
•Occurs when large areas of rock are under
intense heat and pressure.
•Pressure squeezes their grains closer
together. The squeezing makes them more
dense and less porous.
•The heat and chemicals may
rearrange the particles. Making lines
and bands in the rocks.
Contact
Metamorphism.
Diagram
•This process occurs when hot
magma forces its way into overlying
rock. The heat of the magma bakes
the rocks that are in contact with it.
Relation of common Sedimentary
materials and rocks and the
metamorphic rocks page 111.
Examples of metamorphic rocks
and their origin rock.
Formation of Gneiss
• Forms when Granite or
Conglomerate rock is
changed.
Rock Cycle & Rock Review
Comp book Assignment
1. Reviewing Key Terms pg. 119 #’s 1-6
2. Checking Concepts pg. 120 #’s 7-12
3. Applying Skills pg. 120 #’s 17-20