Geology Exam 2

Front 1

Types of Volcanoes

Back 1

1. Shield Volcanoes

2. Cinder (Splatter) Cones

3. Composite Cone (Stratovolcanoes)

4. Massive Caldera

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Shield Volcanoes

Back 2

Low Silica content, high Iron.

Erupts effusively (not very destructive or explosive)

Contains mafic rocks.

May appear on MORs, hot spots

Approx. 200 km.

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Cinder Cones

Back 3

Also known as splatter cones. (Usually grow on side of larger volcanoes)

Low Silica content, high Iron content.

Erupts splatter-like (lots of volatiles)

Contains glass rocks.

May appear on MORs, hot spots

Approx. 2 km.

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Composite Cone

Back 4

Also known as stratovolcanoes. (Has typical "volcano" shape)

High Silica content, low Iron content.

Erupts explosively, (releases gases).

Contains fine-grained rocks (rhyolite, andesite)

May appear on convergent margins (subduction zones)

Approx. 10 km.

Front 5

Massive Caldera

Back 5

Extremely high Silica content, low Fe. (Very viscous and explosive)

Erupts explosively and catastrophically.

Contains tuff (ash fall), volcanic breccia, and rhyolite.

May appear on hot spots (continental crust), subduction zones.

10s to 100s of km.

Front 6

Intrusive Magma Geometries

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Tabular (or sheet) intrusions

1. Dike

2. Sill

3. Laccolith

Front 7

Magma Dike

Back 7

Tabular intrusion that cuts across pre-existing layering in a magma chamber.

Front 8

Magma Sill

Back 8

Tabular intrusions that cut parallel to layering in magma chamber.

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Magma Laccolith

Back 9

Tabular intrusions that started to inject between layers, then domed upward. Creates a "Mushroom" shape.

Front 10

Magma Processes

Back 10

1. Thermal Metamorphism

2. Thermal Shattering (stoping)

3. Ductile Deformation

4. Magma mixing

5. Assimilation

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Thermal Metamorphism

Back 11

"Baking" of host rocks

Front 12

Thermal Shattering

Back 12

Stoping.

Hot magma shoots out to cool rock wall.

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Ductile Deformation

Back 13

Bending rocks around from heat of magma.

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Magma Mixing

Back 14

Different magmas mingling together.

Front 15

Assimilation

Back 15

Melting of host rock.

Front 16

Classification of Igneous Rocks

Back 16

Texture and Composition

-Crystalline

-Glassy

-Pyroclastic

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Crystalline Igneous Rocks

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Distinguished by silica content (felsic, intermediate, mafic, and ultra-mafic) and textural class (coarse grain or fine grain)

e.g. rhyolite, gabbro, diorite, granite

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Glassy Igneous Rocks

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More commonly felsic rocks (high silica content inhibits growth of crystals). Lava that cools rapidly while containing a high concentration of gas bubbles turn into rocks with open holes (vesicles).

e.g. obsidian, pumice, scoria

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Pyroclastic Igneous Rocks

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Pyroclasts = fragmented volcanic debris.

Pyroclastic rock = pyroclasts cemented together.

Distinguished by grain size.

e.g. tuff, volcanic breccia

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Viscosity

Back 20

Resistance to flow.

High viscosity = stickiness

i.e. silica

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Volatiles

Back 21

Elements or compounds, like H2O and CO2, that evaporate at relatively low temperatures and can exist in gaseous form on earth's surface.

Front 22

Magma Compostions

Back 22

Felsic (high silica)

Intermediate

Mafic (high iron)

Ultra-mafic

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4 Types of Sedimentary Rocks

Back 23

1. Clastic

2. Biochemical

3. Organic

4. Chemical

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Clastic Rocks

Back 24

Rocks made of cemented sediment.

No fundamental change in chemistry or mineralogy.

e.g. shale, sandstone, conglomerate, breccia

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Biochemical Rocks

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Biologic and chemical processes.

e.g. fossiliferous limetsone, micrite (from CaCO3 "ooze"), chert (from Si "ooze")

Front 26

Chemical Rocks

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Chemical reaction (precipitin from water).

e.g. rock salt, rock gypsum, travertine (CaCO3)

Front 27

Organic

Back 27

Made of C and H. Decaying of plant minerals.

e.g. coal

Front 28

Sedimentary Rock Environments

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1. Glacial

2. Mountain Stream

3. Alluvial Fans

4. Desert

5. Fluvial

6. Delta

7. Clastic Shallow Marine

8. Carbonate Shallow Marine

9. Deep Marine

Front 29

Glacial Environment

Back 29

2 Types: Mountain (high elevation) and continental (high latitude - polar locations)

Ice "flow" processes. Contains glacial flour and diamictite (glacial breccia)

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Mountain Stream Environment

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High gradient and high velocity.

Water processes (always flowing).

Sediment contains boulders, cobbles, pebbles, and sand (little mud).

Rocks contain conglomerate and sandstone.

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Alluvial Fan Environment

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Similar to mountain stream, by arid.

High gradient.

Intermittent water flow (flash flood)

Mudslides common.

Sediment contains boulders, cobbles, pebbles, and sand (very muddy).

Rocks contain sandstone and breccia.

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Desert Environment

Back 32

Flat and arid. Low precipitation.

Wind and intermittent flow (flash flood) processes.

Sediments contains muds, sand.

Rocks contains breccia (if alluvial fan nearby), sandstone, ripples, and dunes.

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Fluvial Environment

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Meandering "lazy" river. Flows gently.

Flowing water and occasional flood processes.

Sediment contains sand, silt, clay, and mud.

Rocks contain sandstone, siltstone, mudstone (shale).

Front 34

Delta Environment

Back 34

River drop-off in ocean. High volume of sediment, high organic content.

Flowing water and decomposing vegetation processes.

Sediment contains sand, silt, mud, and clay.

Rocks contain sandstone, siltstone, shale, and coal.

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Clastic Shallow Marine Environment

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Beaches and off-shores.

Unidirectional (where sediment enters ocean) and bidirectional (tides or streams) flow processes.

Sediment contains sand, silt, and clay.

Rocks contain sandstone, siltstone, and shale.

Cannot co-occur with carbonate.

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Carbonate Shallow Marine Environment

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Biochemical processes (organisms grom CaCO3).

Sediment calcite, shells.

Rocks contain limestone (micrite and fossiliferous)

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Deep Marine Environment

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Unidirectional flow, bottom current, and pelagic rain (organism "ooze") processes.

Rivers and earthquakes bring in sediment.

Sediment contains clay, calcite, and silica.

Rocks contain shale, chert (Si) and micrite (CaCO3)

Front 38

Weather vs Climate

Back 38

"Climate is what you plan for, weather is what you get."

Front 39

Climate Proxies

Back 39

Data sets for climates

-Instrument records

-Historical records

-Tree rings

-Pollen from lake bottoms and bogs

-Oxygen isotope ratios from ice

-Glacial evidence

-Plankton and isotopes from ocean sediment

-Rocks and fossils

Front 40

Level of CO2

Back 40

Present day: 400 ppm

Front 41

Weather

Back 41

The state of the atmosphere at a particular location and time.

Front 42

Climate

Back 42

A representation of a regions weather over a given period of time.

To have enough data for a record of climate, you need at least 30 years of weather records.

Front 43

Albedo

Back 43

Percentage of light reflected when an object is illuminated.

Reason you wear white on a hot day.