2. What is a rock?
A rock is a naturally occurring aggregate minerals and/or her rock fragments
3. How do Rocks form?
• How much time does it take to form a rock?
• If you squeeze and heat a rock for a
few million years, it can turn into a
new kind of rock.
4. Continued…
• Where does the heat come from?
• When rocks are close enough to the magma to be
heated but not close enough to be melted, the
rocks can be changed.
5. Continued…
• Where does the pressure come from?
• Rocks below the surface are squeezed by the
layers of rock above them. The thicker the
layers, the more pressure there is.
6. If you were to ask a geologist
what the earth is …
What do you think the
response would be?
7. Diagram of the Interior of
the Earth
Crust
0 to 40 km
0°C
Upper Mantle
40 to 670 km
1,000°C
Lower Mantle
670 to 2,890 km
2,000°C
Outer Core
2,890 to 5,150 km
3,700°C
Inner Core
5,150 to 6,370 km
4,300°C
8. What makes up the earth?
Crust
1%
Mantle
69%
Core
30%
Crust
Mantle
Core
9. lets move to some of the
smallest components of Geology …
Now that we better understand the
largest components of Geology …
10. .
Minerals make up rocks.
Natural compounds
and elements combine
to form minerals.
Elements combine to form
the natural compounds.
Rocks make up the Earth.
There is a hierarchy to the
elements of Geology
Atoms make up elements.
11. Elements can be arranged, based on their
identifiable properties, into the Periodic Table
Atomic Theory proposes that all matter is
composed of the atoms of about 100 different
chemical elements. It further proposes that
chemical compounds are formed by the combination
of the atoms of different chemical elements.
12. Only eight elements make up over 98%
of the earth’s crust!
Mg
Na
K
O
Si
Al
Fe
Ca
13. What is the difference between
rocks and minerals?
• A mineral is a nonliving solid found in
nature.
• But, aren’t rocks nonliving and found in
nature too??
• Then what is the difference between a
rock and a mineral?
14. Rocks and Minerals
• Rocks are made up of one or more
minerals!!!
• The reason why some rocks have
more than one color, is because
they contain more than one
mineral.
• Also, some rocks are made of
other things, such as sand and
pebbles, in addition to minerals.
15. Igneous rock is formed from molten rock that has cooled
and hardened.
Sedimentary rock is formed from material that has settled
into layers and hardened.
Metamorphic rock is a rock that has changed by heat and
pressure.
What are the 3 types of Rocks?
26. is a sequence of events involving the formation, alteration,
destruction, and reformation of rocks as a result of natural
processes ...
Glossary of Geology, Bates & Jackson, AGI
RockCycle
31. Definitions
Definitions
• Metamorphic Rock
- "Meta"= Change (Grk)
- "Morph"= form (Grk)
• Metamorphic Rock
- "Meta"= Change (Grk)
- "Morph"= form (Grk)
- a rock that has been changed
from its original form ( parent ) by
heat , pressure , and fluid activity
into a new rock ( daughter ).
- a rock that has been changed
from its original form ( parent ) by
heat , pressure , and fluid activity
into a new rock ( daughter ).
Metamorphic Rocks
Metamorphic Rocks
32. Heat
Heat
• Magma
- temperature of magma
- composition of magma
• Magma
- temperature of magma
- composition of magma
• Geothermal gradient
- temperature increases with depth of burial
- core of Earth is warmer than outer crust
• Geothermal gradient
- temperature increases with depth of burial
- core of Earth is warmer than outer crust
Sources Include.....
Sources Include.....
33. Uniform Pressure
Uniform Pressure vs Directed Pressure
• Lithostatic
- "Lithos"= rock, static= unchanged (pressure)
- uniform (aka non-directed)
- equal intensity from all directions by rocks
• Lithostatic
- "Lithos"= rock, static= unchanged (pressure)
- uniform (aka non-directed)
- equal intensity from all directions by rocks
37. Types of Metamorphism
Types of Metamorphism
• Contact
- caused by igneous activity
• Dynamic
- aka cataclastic
- associated with faults & earthquake zones
• Regional
- caused by tremendous pressures
associated with tectonic plate activity
• Contact
- caused by igneous activity
• Dynamic
- aka cataclastic
- associated with faults & earthquake zones
• Regional
- caused by tremendous pressures
associated with tectonic plate activity
38. Contact Metamorphism
Contact Metamorphism
• Igneous Intrusions
- size and type of magma important
> mafic magma hotter than felsic
- heat decreases away from magma
> forms a zone of altered country rocks called Aureoles
• Igneous Intrusions
- size and type of magma important
> mafic magma hotter than felsic
- heat decreases away from magma
> forms a zone of altered country rocks called Aureoles
39. Dynamic Metamorphism
Dynamic Metamorphism
• aka Cataclastic Metamorphism
• associated with Fault Zones
- Places where the Earth's crust ruptured
- Rock pulverized
> heat and pressure come from movement along the
Fault
• resultant rock is known as a Mylonite
• aka Cataclastic Metamorphism
• associated with Fault Zones
- Places where the Earth's crust ruptured
- Rock pulverized
> heat and pressure come from movement along the
Fault
• resultant rock is known as a Mylonite
40. Regional Metamorphism
Regional Metamorphism
• Most common form of metamorphism
• caused by large scale forces
- lithospheric plate collision
• covers very large areas
- metamorphic belts or zones
- Zones are characterized by Index Minerals
> form under specific temperatures and pressures
> metamorphic facies
• commonly associated with
- shields: stable areas of crystalline rocks
• Most common form of metamorphism
• caused by large scale forces
- lithospheric plate collision
• covers very large areas
- metamorphic belts or zones
- Zones are characterized by Index Minerals
> form under specific temperatures and pressures
> metamorphic facies
• commonly associated with
-
Shields and Mountains: areas of crystalline rocks
41.
42. Metamorphic Textures
Metamorphic Textures
• Foliated
- Folios = page or leaf-like
- rock has distinct banding or layering
> often not smooth like in sedimentary rocks
- formed under directed pressure
• Non-foliated
- no distinct layering character
- often a massive crystalline texture
- formed under uniform pressures
• Foliated
- Folios = page or leaf-like
- rock has distinct banding or layering
> often not smooth like in sedimentary rocks
- formed under directed pressure
• Non-foliated
- no distinct layering character
- often a massive crystalline texture
- formed under uniform pressures
45. Foliated Textures
Foliated Textures
• Slatey
- looks like blackboard
> dull surface
- smooth, thin layering
- breaks into flat slabs
> referred to as slatey cleavage
- no mineral grains visible
• Phyllitic
- looks like waxed surface
> has a "sheen" to it
- may have little "waves" on
surface
> referred to as crenulations
- some small grains visible
• Slatey
- looks like blackboard
> dull surface
- smooth, thin layering
- breaks into flat slabs
> referred to as slatey cleavage
- no mineral grains visible
• Phyllitic
- looks like waxed surface
> has a "sheen" to it
- may have little "waves" on
surface
> referred to as crenulations
- some small grains visible
• Schistose
-
- visible grains
> garnets, staurolites
- may have shiny
> due to mica minerals
• Gneissic
- larger grains
- may look like igneous rock
- may have crude banding
> intensely distorted
- different minerals than
schistose
• Schistose
- distinct bands of minerals
- visible mineral grains
> garnets, staurolites
- may have shiny
appearance
> due to mica minerals
• Gneissic
- larger grains
- may look like igneous rock
- may have crude banding
> intensely distorted
- different minerals than
schistose
46. Foliated MM Rocks
Foliated MM Rocks
slate
slate
schist
schist gneiss
gneiss
phyllite
phyllite
MM Rocks that could form as a shale (sedimentary) parent rock is
MM Rocks that could form as a shale (sedimentary) parent rock is
exposed to increasing directed pressure and temperature
52. MAGMA
• Molten Rock
• Usually with dissolved gasses
• Generated at depth
• Eruptions if magma (lava) reaches surface
• If doesn’t reach surface, Solidifies underground
• Intrudes country or host rock
• Intrusive contact
• Xenolith- ‘foreign body’
53.
54. Igneous Rocks
• Names based on mineral composition
reflects chemical composition of the
magma and...
Grain size
• Very coarse-grained Pegmatitic
• Coarse-grained: Phaneritic > 1 mm.
• Fine-grained: Aphanitic < 1 mm.
• Porphyritic- 2 crystal sizes
61. Igneous Rock Identification
• Granite (& Rhyolite)
• High in Si + O
• Low in Fe + Mg
• Mostly feldspar & quartz
• Light-colored
• Basalt (& Gabbro)
• “Low” in Si + O
• High in Fe + Mg
• no quartz, abundant ferromagnesian minerals
• Dark colored
• Andesite (& Diorite- intermediate)
62.
63.
64.
65.
66.
67. Sedimentary Rocks
How They are Made
• Wind and water break down the earth
• Bits of earth settle in lakes and rivers
• Layers are formed and build up
• Pressure and time turn the layers to rock
1. Weathering and erosion
2. Transportation
3. Deposition
4. Consolidation and cementation
69. WEATHERING, EROSION,
TRANSPORTATION
• Weathering- Physical disintegration and chemical
decomposition of rocks
• Erosion- Physical removal
• Transportation- Movement of eroded particles
• Chemical vs. Physical Weathering
• Effects of weathering
• Surface alteration of outcrops
• Spheroidal weathering
• Differential weathering
