final exam

Geology 101 with Baker at University of Tennessee - Knoxville

About this deck

By: Alex Mullican
Textbook:

Earth: An Introduction to Physical Geology (10th Edition)
Created: 2010-12-01
Size: 89 flashcards
Views: 349

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3 types of plate boundaries and if they can have volcanoes

convergent- volcanoes

transform- NO volcanoes

divergent- volcanoes

island arc

-oceanic-oceanic convergent

-new continental crust formed

volcanic arc

-200-300 km island

-oceanic-continental

-new continental crust formed

hot spots..... aka intra-plate volcanism

-completely UNrelated to plate boundaries

-form at hotter than normal regions in the asthenosphere

-theorized to be related to disturbances in the earths core

volcano

a vent in the surface of the earth through which magma and associated gasses and ash errupt

3 Kinds of Extrusive Igneous Material--what comes out of volcanoes

-pyroclastic debris(tephra): solid
-lava: liquid
-gas: gas

What are the two kinds of lava?

- aa lava: high viscosity, thick moving, thick lava
- pahoehoe lava: low viscosity, fast moving, thin and runny lava

Pyroclastic Debris

-based on size
-ash: dust
-cinders: lappilli
-volcanic bombs: size of fist to larger size of motor home

Gas is made of:

-steam- H2O gas
-CO2
-sulfur gas
-chlorine
-fluorine
-nitric acid

Important Parameters in Volcanic Explosiveness

1. Viscosity
2. Magma Chemistry
3. Gas Content of Magma
4. Water Content of Magma

Viscosity

-the “thickness” of a fluid (honey-high, water-low)

Low Viscosity Lava

-tends to erupt in nonexplosive manner
-form volcanoes with gentle slopes
-pahoehoe lava

High Viscosity Lava

-tends to erupt in explosive manner
-form volcanoes that have steep sides
-aa lava

Magma Chemistry

-a contributing factor in the viscosity of magma
-describes the elements present
-silica: most important (SiO2)
-typically between 50 and 70% silica content
-silica links together into chain structures (like spaghetti); the more silica, the more chains, the more viscous
-gas

Gas Content of Magma

-as soon as the pressure keeping the gas dissolved in the magma is let off, it lets the gas out
-like coke
-the amount of gas within magma also contributes to the type of eruption that occurs
-as magma rises to the surface of the earth and decompresses, the gas within the magma decompresses typically violently
-when silica content is low, the gas can more easily escape because there are fewer noodles

Water Content of Magma

-water is intermixed in the magma in the liquid form and does not boil because of the amount of pressure it is under
-as an eruption occurs however, the magma decompresses the liquid water flashes to steam(gas) and violently expands

Volcanic Explosiveness

Explosive-----------------------------------Less explosive
Viscosity----------------------------less viscous
High silica content---------low silica content
More gas--------------------------------less gas
More water---------------------------less water

What are the 2 types of Eruptions?

-Pyroclastic Eruption:
-explosive
-associated with pyroclastic debris
-may or may not have associated lava flow
-Lava Fountain:
-less explosive
-associated with lava extrusion
-may or may not have associated pyroclastic debris

What are the 6 types of volcanoes?

1. Lava Plateaus
2. Shield Volcanoes
3. Strato Volcanoes
4. Cinder Cones
5. Lava Domes
6. Caldera

Lava Plateaus

-erupt out of fissures
-nonexplosive (lava flow eruption)
-low silica content- 50%
-low gas
-very low viscosity
-forms extensive flat-lying plateaus of basalt
-ex. Columbia River Plateau, Snake River Plateau

Shield Volcanoes

-erupt out of central region
-nonexplosive (lava flow eruption)
-low silica content 50%
-low gas content
-low viscosity
-form as low but wide gently-sloped volcanoes
-also formed mainly basalts
-ex. Hawaiian Islands

Stratovolcanoes

-erupt put of central region
-Explosive! (pyroclastic eruption)
-moderate silica content 60%
-higher gas content
-moderate viscosity
-lava flows ARE present
-form as steep-sided volcanoes
-alternating layers of lava and pyroclastic debris
-formed mainly of andesite (medium silica-content extrusive igneous rock)
-ex. Andes Mountains

Cinder Cones...aka Scoria

-erupt out of central regions
-explosive (pyroclastic eruption)
-low silica content 50%
-high gas content
-very low viscous lava
-form when frothy magma spits out of a central vent, bits cool into cinders, and fall into a pile around the vent
-ex. Craters of the Moon

Lava Domes

-erupt out of central region
-nonexplosive (lava flow eruption)
-high silica content
-low gas content
-very high viscous lava
-domes are typically formed out of rhyolite(high silica-content igneous extrusive rock)
-can form within the crater of a larger volcano
-ex. Dome within the crater of Mt. St. Helens

Caldera

-similar to stratovolcanoes but much LAGER
-almost all types of lava and rock types can be found
-typically INITIALLY very explosive

Plate Tectonic Settings of Volcanoes

1) divergent boundaries
continental-continental: lava plateaus (basalts); cinder cones
oceanic-oceanic: lava plateaus (basalts)
2) convergent boundaries
oceanic-oceanic: stratovolcanoes (andesite)
continental-oceanic: stratovolcanoes (andesite)
3) hot spots
Lava plateaus (basalt); shield volcanoes (basalt, andesite); Caldera eruptions (various)

6 Volcanic Hazards

1. Gas
2. Lahar
3. Mass Wasting
4. Lava Flows
5. Pyroclastic Flow
6. Tephra

Gases that pose the greatest potential hazard

-sulfur dioxide
-carbon dioxide
-hydrogen fluoride

sulfur dioxide

-acid rain, kill crops etc.
-short term

carbon dioxide

-global warming
-long term
-large number of people and animals can be killed
-pretty dense gas and therefore in rare cases you can have invisible massive flows of gas
-causes suffocation

hydrogen fluoride

-lands on plants-animals eat and get fluoride poisoning---bones turn to jello
-have been some cases where people eat the affected animals and also get fluoride poisoning

Lahar

-MOST UNPREDICTABLE
-can easily grow to more than 10 times its original size
-volcano related mud or debris flow
-hot or cold mixture of water and rock fragments flowing down the slopes of volcanoes and/or river valleys
-vary tremendously in size and speed
-its size, speed, and amount of water and rock debris it carries constantly changes
-depends on what it flows over-- snow field melts snow makes lower viscosity goes faster

3 Causes for Lahars

-happen during eruptions
-melting of snow and ice by pyroclastic flows and lava flows
-happen after eruptions
-heavy(can be normal) rainfall can lead to erosion and lahars
-sudden release of water by lake breakouts (can be 6-8 months after eruption)
-can happen without eruptions
-sudden landslides at volcanoes can trigger lahars
-cold lahar; not related to eruption

Mass Wasting

Because:
1. Tall/ steep sided
2. Inherently unstable
-intrusion of magma
-explosive eruptions
-large earthquakes directly beneath or near volcano
-intense rainfall that saturates a volcano

Lava Flows

-because of the speed at which it moves
1. Type of lava erupted and its viscosity
2. Steepness of ground over which it travels
3. Whether the lava flows as a broad sheet, through a confined channel, or down a lava tube
4. Rate at which lava is produced

Pyroclastic Flows

-high density mixture of hot, dry rock fragments and hot gases that move away from the vent that erupted at high speeds
-they may result from the explosive eruption of molten or solid rock fragments or both(like they’re on an air hockey table)
-they may also result from the nonexplosive eruption of lava when parts of dome or a thick lava flow collapse down a steep slope

Tephra

-general term for fragments of volcanic rock and lava regardless of size that are blasted

Run-off

-surface flow of water that appears after precipitation

Stream

-any body of water confined within a channel, REGARDLESS of size

Drainage Basin

-the region from which a stream draws water

Tributary

-a stream that feed, flows into, or joins a larger stream or lake

The size of a stream..

-at any point is related to the size of the drainage basin upstream from that point
-its also influences by climate, vegetation(or lack thereof), and geology

Stream Morphology

-the study of channel pattern and channel geometry at several points along a river channel, including the network of tributaries within the drainage basin

4 types of drainage patterns

-radial pattern … kind of like a star
-dendritic pattern … kind of like a tree
-trellis or lattice pattern … kind of like stone wall-kind of wiggly
-rectangular pattern … looks like brick pattern-less wiggly than trellis

Flood plain

-relatively smooth valley floors, adjacent to and formed by alleviating streams subject to overflow

Alluvium

-the detrital materials(sediment) that are eroded, transported, and deposited by streams

Bedrock

-general term applies to the solid rock underlying soil(regolith) or any other unconsolidated superficial cover

Factors of stream erosion and deposition

-velocity
-discharge
-stream gradient

Velocity

-the speed and direction of stream flow in units of distance per time
- meters/second

Discharge

-volume of water passing a point in a stream in a certain amount of time
- cubic meters/second or liters/second
- discharge = velocity x cross-sectional area

Stream Gradient

-the steepness of the stream channel measured as the vertical drop per unit of horizontal distance
-slope….
- meters/kilometers…. Height/distance

3 Processes of Stream Erosion

-hydraulic action
-solution
-abrasion

Stream Transport

1. Load of the stream
A. Bed load
-traction
-saltation
B. Suspended load
C. Abrasion
2. Measure of transport
A. Capacity
B. Competence

Erosion vs. Deposition

-a stream can BOTH erode (channels) and deposit (eroded material) along its length, and even from one bank to the other

Graded Stream

- the process by which over time, the stream gradient is adjusted yield the velocity required for transportation of the load supplied from the drainage basin

Base Level

-the lowest elevation to which a stream can erode downward
Ultimate base level= sea level
Local base level= may be a pond, lake, reservoir, etc.

Hydrologic Cycle

-the complete cycle through which water passes from the ocean, through the atmosphere, to the land, and back to the ocean.
-aka the water cycle

Evaporation

-takes place on exposed bodies of water (streams, lakes, seas, oceans, etc.)
-depends on….
-the availability of water
-the regional climate -H2O as liquid becomes H2O gas
-water gas is invisible to the human eye
-steam is a liquid, clouds are liquid

Condensation

-the process by which water vapor becomes a liquid
-brought about by:
-cooling of air to its dew point
-addition of enough water vapor the bring the air mass to the point of saturation

Precipitation

-any or all of the forms of water particles, whether liquid or solid, that fall from the atmosphere and reach the ground

Run off

-surface flow of water that appears after precipitation
-either sheet flow or channel flow

Infiltration

-the movement of water through the soil surface into the ground

Through-flow

-slow migration of water in the unsaturated zone
-path of movement controlled by both gravity and capillary action(what makes paper towels work)

Base-flow

-flow of water entering water basins within the saturated zone under the influence of gravity

Transpiration

-discharge of water to the atmosphere by plants
-occurs as:
-evaporation of water on plants from precipitation
-evaporation of water at the surface of the foliage

9 Stream Depositional and Erosional Features

1. Bar
2. Meandering Stream
3. Braided Stream
4. Levee
5. Delta
6.Alluvial Fan
7. Lateral Erosion
8. Base Level Rise
9. Floods

Bar

-depositional feature
-an elongate ridge, bank, or mound of gravel deposited by water action

Meandering Stream

-point bar:
-depositional feature
-a low ridge deposited on the inside of a growing meander
-cut bank:
-erosional feature
-a steep or overhanging slope on the outside of the meander curve
-produced during sideways erosion of a stream
-oxbow lake:
-depositional feature (as the lake fills in with sediment)
-a crescent shaped body of standing water created during a meander cutoff

Braided Stream

-erosional and depositional feature
-found around mountains

Levee

-depositional feature
-an embankment of sediment(or man-made material) on one or both sides of a stream
-can be natural or man-made

Delta

-depositional feature
-nearly flat alluvial deposits at the mouth of a river
-commonly forming a triangular or fan shape

Alluvial fan

-depositional
-an outspread, sloping mass of alluvium deposited by a stream
-deposited in arid or semi-arid climates where the stream issues from a narrow canyon into a valley floor

Lateral erosion

-erosional feature
- stream terraces:
-one or more of a series of level surfaces above the stream channel
-remnant of an older flood plain

Base level Rise

-erosional feature
- incised(cut) meanders:
- an old stream that has become deeper by rejuvenation

Floods

-mainly depositional feature
-create sequences of deposited alluvium that are finer-grained away from the stream channel

4 stages of stream development

1. Youthful(v-shaped valley)- no flood plains
2. Mature- flood plain perfectly fits the meander bends
3. Old-age: flood plains are much larger than the meander bends
4. Rejuvenated- can tell you how old landscape(environment is)

Ground water

-the part of the subsurface water that is in the zone of saturation

Porosity

-the ratio of void space in a rock to its total volume (%)
-100% porosity is air

Permeability

-the capacity of a porous rock, sediment, or soil for transmitting a fluid; its measure is the relative ease of fluid flow under unequal pressure
-aka hydraulic conductivity

Porosity generally increases when…

1. Amount of sorting increases (grains are well sorted, i.e. The same size)
2. Fracturing increases
3. Grain shape is more spherical

Permeability generally increase when…

1. Amount of sorting increases
2. Fracturing increases
3. Grain size increases (due to surface tension)

A good long term source of groundwater must have…

-high porosity AND permeability

Water table

-the boundary between the zones of aeration(vadose zone) and zone of saturation

Aquifer

-a body of rock that is sufficiently permeable to conduct groundwater and has sufficiently high porosity to yield a large amount of water to wells and springs

Unconfined Aquifer

-an aquifer which is not bound on top by any layers

Confined Aquifer

-an aquifer bound above and below by impermeable or very low permeability layers

Aquitard

-a confining layer that retards the flow of water to or from an adjacent aquifer
-typically characterized by very low permeability

Potentiometric Surface

-an imaginary surface representing the level to which water would rise in a well

Cone of Depression

-a depression in the water table or potentiometric surface which develops around a well from which water is being withdrawn

About this deck

By: Alex Mullican
Textbook:

Earth: An Introduction to Physical Geology (10th Edition)
Created: 2010-12-01
Size: 89 flashcards
Views: 349

About StudyBlue

“Simply amazing. The flash cards are smooth, there are many different types of studying tools, and there is a great search engine. I praise you on the awesomeness.”
Dennis