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GEO 101: FINAL EXAM
Can you pump a well dry? |
yes
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Caves and Karst landscapes are composed of |
groundwater and limestone
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What does the rock cycle tell us?
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-any type of rock can be reformed into any other type of rock!
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What does Bowen’s reaction series tell us? |
explains why certain types of minerals tend to be found together while others are almost never associated with one another. one can infer from the minerals present in a rock the relative conditions under which the material had formed.
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Why is gravel the first particle to be deposited as energy decreases in a fluid system? |
Because its heaviest?
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at which tectonic plate boundary are you most likely to see deep earthquakes? |
Convergent
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what causes foliation in metamorphic rocks?
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foliation forms by rotation and recrystallization of elongated minerals
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sinkhole |
individual cave that collapsed
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Flowstone |
Sheets of water down walls. Makes cave bacon
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Stalagmites |
mound of calcite on the floor
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Stalactites |
not hollow, water drips off end, grows like calcium icicle
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Speleoth
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calcium filled water
-evaporates and deposits calcite
-makes stalactites and stalagmites
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How are caves formed?
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groundwater absorbs CO2
-becomes weak acid
-dissolves carbonate rock (limestone)
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Land Subsidence
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you can bring the land down over a meter by pumping water
-New Orleans, levee sunk & no one measured it so it failed.
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Ways to deplete our groundwater supply
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-lowering the water table
-Reversing flow
-saline intrusion: drill well near ocean area and cone of impression forms bc u pump out more water, salt water is beneath the fresh water.Sometimes you can suck in the salt water through the cone of impression.
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How does hot water make it to the surface?
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magma near earths surface (geothermal regions)
(water flows so deeply that it gets heated by geothermal energy)
-deep groundwater forced up by pressure or a pathway.
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Spring |
any place where groundwater naturally flows to the surface
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Types of wells
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Ordinary well
Seasonal well
Artesian Well
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Artesian Well- |
works like water tower (high pressure moving to low pressure)
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Seasonal well |
- only get water out during the rain season
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Darcy's Law
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-More permeable= faster
-Steep slope= faster
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2 things that make groundwater move:
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gravity
pressure
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Perched water table |
one with a little hump of water over it. Confined.
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Water table |
above it most spaces are filled with air, below it most spaces are filled with water. Follows land surface.
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Aquifer |
a porous deposit of rock, such as a sandstone, containing water that can be used to supply wells
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Permeability
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: the ease in which the water can flow.
-gravel (rapid drainage), fine sand, clay (mod. drainage), solid rock (slow/no drainage)
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Porosity |
measurement of pore space.
-different material gives a different amount of space
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Groundwater
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Water that sinks to the ground through gravity or gets trapped in rock during formation
-months to thousands of years
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Karst Landscapes
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-formation:
-water table in limestone
-caves form
-water tables sinks, new caves form
-some caves start collapsing
-features: hummocky (weird looking mountains)
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5 TYPES OF DESERTS
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5 types of deserts
-Subtropical deserts
-Rain Shadow desert
-Coastal desert
-Continent Interior desert
-Polar desert
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Subtropical deserts |
exist because of poor air circulation
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Rain Shadow desert |
mountain range with tropical forrest on one side and dry on the other side. The Washington and Oregon deserts. This is why it rains all the time in seattle.
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Coastal desert |
Has to be a cold current (coming up from the arctic ocean).
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Continent Interior desert |
as the air flows over a large continent comes out before it reaches the middle. Far from the ocean. Air moisture used over the continent.
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Polar desert |
global air circulation. Coriolis effect.
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Types of desert weathering
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-Physical weathering
-Wedging
-Abrasion
-jointing- under pressure
-biological
-mass wasting
-Chemical weathering
-desert varnish: microbial action on clay.
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Desert erosion
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Water
-flash floods
-high competency and capacity
-stream erosion.
-Wind
-energy level determine grain size
-suspended load
-saltation_stuff rolling across the bottom
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Desert Pavement formation theories
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-Formation theory no.1: over a time the wind blows away the smaller particles and leaves the heavier ones on top.
-Formation theory no.2: Bedrock that has been weathered with large chunks on top. The soil, because there are spaces left, some of it falls down into the cracks and accumulates under the stones and pushes the stones up until you have a bunch of sand beneath the mosaic of stones.
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Alluvial Fan
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abrupt change in velocity. Stream dumps coarse sediment.
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Talus Apron
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pile of debris due to gravity.
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Salt lake |
a lake with no outlet. Water collects and evaporates. Salt concentrates.
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Playa |
a dry lake bed
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Dunes
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There are different types created by the amount of sand available and the wind direction and speed wind moves sand and carries small grains away. Larger grains only move so far.
-Formation: sand blows up one side.
Cross bedding
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Mesa/bute/chimney |
big flat top mountain. Mesa biggest, bute smaller, chimney smallest.
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Desertification
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-changing something that isn’t a desert into a desert
Cause: deforestation, drought, water mismanagement, agriculture, overgrazing.
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What is the scientific method?
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Scientific method: natural process has four major sections: determining what the question is, testing ideas (most of work in science gets done.. have hypothesis here), community analysis and feedback (this is where theory building occurs.. that explains the big picture), benefits and outcome
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What are the major rock types? |
Igneous, Metamorphic & Sedimentary
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How do we date rocks?
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-superposition
-absolute dating (radiometric, layer counting)
-relative dating (cross-cutting relationship)
-fossils
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what happens at each tectonic boundary? |
-what happens at each tectonic boundary
-geo features
-rocks
-faults
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Continental Shelf
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anything that is underwater but is continental crust
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Continental Margins |
active (tectonic plate sliding under another) passive (two tectonic plates that aren’t moving or is just one large tectonic plate)
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Canyons |
rivers, turbidity currents
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Continental Slope
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-continental slope: usually steep
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Abyssal Plain
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flat part of the very very deep ocean
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seamounts
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seamounts are underwater mountains that never make it above water
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Sea Water
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-3.5% salt
-halite, gypsum
-dense
-salinity depends on location and temperature... salt water is denser than freshwater
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Currents
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flowing water in defined area
-surface currents
-deep currents
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surface currents
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driven by wind/Coriolis effect (because the earth is always moving in one direction)
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deep currents |
caused by downwelling and upwelling, also Coriolis effect, density (thermohaline circulation)(temperature and salinity)
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Tidal Reach
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The elevation difference between high and low tide
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Wave Length
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is the difference between wave crests
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trough |
The low part of the wave
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Open Ocean Waves
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energy move forward but water stays put
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Longshore Current
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underwater current that runs next to the shore.. whenever the wave energy comes in and out the particles of sand will be moved over
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Wave Refraction
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force that helps waves hit the beach in a parallel way (determines how things are eroded)
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Translational wave
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friction between wave and ocean floor
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Types of coastlines |
Beach
Tidal flat
rocky coast
coastal wetlands
coral reefs
estuaries
fjords
barrier island
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Beach
|
nearshore zone, intertidal zone, backshore, dunes
-dynamic (sand always moving)
-some beaches grow, others being eroded
-high tide: covered by water
-low tide: exposed mud/sand
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Barrier Island |
sand islands, always changing
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Rocky Coast |
embayment, headland, always
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Coastal Wetlands
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-shallow water
-no wave action
-temperate climate: see grassy flats (salt marsh)
-subtropical climate: mangrove swamp
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Coral Reefs
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-shallow, warm
-grows until conditions change
-erode into coral sand
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Estuaries
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any place the ocean meets freshwater
-ocean rises into river valley
-mix of fresh and salt water = brackish water
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Fjords |
glacial valley, flood after glaciers melt
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What determines type of coast?
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-tectonic setting
-climate
-sea level
-sediment supply
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Types of defense against imminent sea level rise
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-Beach erosion
-groin: barrier built to keep sand from eroding.. once one person decides to put one up all the neighbors on the coastline have to
-jetty: protect harbor entrance
-breakwater: decreases wave energy
-rip rap: decrease wave energy
-beach nourishment: bring in new sand
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Why is New Orleans below sea level?
|
human activity
-wetland removal, no where for water to go
-artificial levees
-no new sediment
-extracting groundwater
-compacting sediment
-isostacy: lithosphere maintaining equilibrium
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The Hydrologic Cycle
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-circulation of Earth’s water supply
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sheetwash
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water comes down in sheets because there is no stream
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Rills
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takes advantage of gravity makes new channel
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Streamflow
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water has eroded and cut into the service so there is a defined channel
-increases as water is added headward erosion
-main channel gets longer
-side channels flow in (tributaries)
-not static
-entire system called drainage network
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Dendritic pattern |
uniform underlying geology and slope, most likely to see in Alabama
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Drainage Basin
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land area contributing water to stream
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Divide
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imaginary line separating one basin from another
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Permanent Stream
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water flows all year at or below water table, humid or temperate climate
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Ephemeral Stream
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does not flow all year (flash floods), about water table, dry climate
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Dry Wash |
Empty stream channel
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Flow Types
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laminar flow: no mixing between layers (calm water)
-turbulent flow- complex mixing
-type depends on velocity and stream characteristics
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What determines water flow?
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What determines water flow?
Stream gradient
Channel characteristics:
-friction slows water
-narrow streams move faster than wide ones
Channel Discharge
Stream Erosion
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Stream Erosion
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-gravity makes water move
-some of this energy erodes the stream
-scouring: remove loose fragment
-breaking and lifting
-abrasion: suspended sediment as sandpaper
-dissolution: dissolves minerals
What characteristics create the most erosion?
-lots of water
-turbulent
-sediment
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Stream Gradient |
slope of stream, vertical change -gradient decreases downstream
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Competence
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maximum particle size stream carries
-high = large particles
-low = small particles
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Capacity
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total quantity of sediment stream can carry
-depends on competence and discharge
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Deposition
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decrease in velocity causes sediment dump, velocity change determines sediment size
-gradient change
-friction with bed increase
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Base levels
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base Level: lowest elevation a stream can reach
-ultimate base level (sea level)
-local base level (lake, resistant, rock, largest stream in area)
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rapid
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rough water
-large debris
-narrow channel
-gradient change
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Waterfalls
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gradient so steep - free fall (usually occur where old shore lines used to be)
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Alluvial Fan
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abrupt change in velocity, stream dumps coarse sediment
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Braided Streams
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stream divide due to sediment, in between floods
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Meandering Streams |
any river or stream that has slow water and is curvy (Black Warrior River is an example).. these form Oxbow Lakes
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Floodplains
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-stream overflows bank - deposits sediment
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Terraces |
remnant of former floodplains
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Deltas
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-running water meets standing water
-velocity change- sediment drops
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Floods
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-most common and destructive geologic hazard
-causes
-sudden heavy rain or snow melt (water can’t soak into the ground fast enough)
-long period of rain (ground become saturated)
-collapse of artificial or natural dam
-Seasonal or Flash
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Human impact on rivers
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-Urbanization: paved areas lead to flooding, water cannot soak in.. and building in floodplains
-Agriculture: 65% of water use from rivers
-increase sediment in streams
-changes stream chemistry: fertilizers, animal waste
-ecosystem change
-Dam Construction
-changes in ecosystem: migrating fish, sediment load, nutrients
-flood control: positive and negative
-Overuse
-Colorado River
-Central Arizona Project canal (water gets evaporated)
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What are metamorphic rocks?
|
other rocks that have been changed by temperature and/or pressure
-Igneous Rocks
-Sedimentary Rocks
-Other metamorphic rocks
-solid state change (NO MELTING)
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Foliated rocks
|
parallel alignment of elongated minerals
-banding of different minerals
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What is the ocean floor made of? |
Basalt
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Divergent Boundary
|
normal faults, igneous rocks, shallow earthquakes
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Convergent Boundary
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-convergent: reverse and thrust faults, metamorphic rocks, deep earthquakes
|
Transform Boundary |
strike slip fault, metamorphic, shallow earthquakes
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Theory
|
a widely accepted explanation for why things happen... differs from a hypothesis in the breadth of what it explains... often includes several hypothesis
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What structures associate with Igneous
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igneous: volcanic, divergent boundaries... giant plutons exist.. doesn’t have to come from volcano
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What structures associate with Metamorphic
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-metamorphic: mountain building activity, convergent plate boundary.. wherever there are plates coming together
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What structures associate with Sedimentary |
-sedimentary: rivers, beaches, desert (wherever there is weathering and erosion)
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Hypothesis |
has explanatory power and can be tested
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Dendritic
|
uniform underlying geology and slope, most likely to see in Alabama
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Can earthquakes be predicted? |
NO
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Hard/Soft water |
Soft water contains more salt
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The Hydrologic Cycle
|
circulation of Earth’s water supply
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Isostacy
|
lithosphere maintaining equilibrium
|
What kinds of formations are common in the desert? |
Mesa, Bute, Dunes, Playas
|
What causes desertification? |
deforrestation
droughtovergrazingh2o mgmtagriculture
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Main causes of desert weathering |
wedging
abraisionbiologicaljointingchemicalmass wastingWATER AND WIND
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What controls the movement of glaciers? |
melting, freezing, gravity, slope
|
surge |
rapid movement of glaciers
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Glacial advancement |
happens when the rate of accumulation is greater than the rate of wastage.
|
____ cut v shaped valleys |
rivers
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____cut U shaped valleys |
glaciers
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Kames/Eskers |
Ice contact deposits by melt water flowing over, in and at the base of motionless ice. Kames look like zits and eskers look like snakes
|
Cirques |
bowl shaped depressions that form at the upper end of glacial troughs
|
Drumlins |
smooth elongated hill in the shape of a spoon. Used to determine direction of ice
|
Moraines |
Ridges made of till (lateral, medial, end)
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How do glaciers cause erosion? |
Plucking/bulldozing-lifting & pushing rox
abrasion- rocks within ice polish surface below and produce glacial striations
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Outwash Plains |
Braided streams and fine grained sed
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Glacial Drift |
all sediments of glacial orgin
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Till |
deposited by ice (sed)
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Stratified drift |
sed laid down by glacial meltwater resulting in braided streams
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Aretes |
A thin ridge formed by the headward erosion of 2 cirques (remember what those are?)
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Horns |
steep wall pyramid peaks
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Hanging Valley Glacier |
a tributary valley whose floor is at a higher level than that of the main valley
|
How do glaciers form |
More snow falls than melts
|
What geological features are created by glaciers? |
Fjords
hanging valleyshornsaretecirques (remember what those are?)truncated spurs?U shaped troughs
|
Firn |
dense granular material created by recrystallized snow with only 25% air
|
2 types of glacial ice |
plastic flow (within) Pressure makes ice behave like plastic
Basal slip (beneath) entire mass slipping alone ground
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Fjords |
Glacial valley flood after glaciers melt
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2 types of glaciers |
Valley ((Flow down from accumulation))
Continental ((greenland & Antarctica))
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Different types of coastlines |
Beach
rocky coastwetlandsbarrier islandestuariestidal flats
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How do humans stabilize coastlines? |
Groin barriers
Jettys- harbor protectionbreakwater/ rip rap to decrease wave energyBRING IN NEW SAND
|
What determines the type of coast? |
tectonic setting
climatesea levelsediment supply
|
Estuaries |
any place the ocean meets fresh water
|
Coastal Wetlands |
shallow grassy no waves
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Wave Refraction |
Force that helps waves hit the beach in a parallel way
|
Open wave |
Energy moves fwd- water stays put
|
Translational Wave |
Friction between wave and ocean floor
|
Trough of wave |
The bottom part
|
Surface Currents |
driven by corollis
|
deep currents |
down/upwelling
coriollisdensity/temp/salinity
|
currents |
flowing water in a defined area
|
What causes tides? |
moons grav
elevation diff between high and low tide
|
What geo features are created by groundwater? |
Caves
KarstSinkholes
|
How does groundwater move through diff seds? |
gravity & pressure
through pores in rox
|
How do humans access groundwater? |
wells, aquifiers in water tables
|
How does groundwater move |
from high to
LOWpressure
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What factors influence groundwater quality? |
septic tanks
farm run offmine run offstorage tanksindustrial landfills
|
How can groundwater be depleted? |
by lowering the water table
reversing the flowsaline intrusionland subsidence
|
What effects do humans have on rivers? |
Urbanization: paved areas= flooding
Agriculture: 65% water use from riversdam construction changes eco systemoveruse
|
What is the recurrence interval and annual probability of floods? |
Recurrence- avg # of yrs btween floods the same size (100 yr floods happen every 100 yrs)
Annual prob- likelihood that flood of a given size will happen @ a specific location during any given year
|
Seasonal flood |
gradually covers floodplain (spring snow melting)
|
Flash Flood |
happens in deserts lots bc it cant absorb the water
quick rise in sea level or intense rain
|
Delta |
running water meets still water
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Floodplain |
stream overflows bank and deposits sed
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Terraces |
Remnant of former floodplains
|
Meandering Streams |
Any river or stream that is slow and curvy
|
Braided Streams |
Streams divide due to sed in between floodz
|
Alluvial Fan |
Abrupt change in velocity
stream dumps coarse sed
|
Competence |
Max particle size a stream carries
|
Capacity |
total quantity of sed carried
|
How do streams erode transport and deposit sed? |
Grav makes water move
scouring- removes loose fragbreaking& liftingdissolution-dissolves mineralsabrasion- suspended sed as sandpaper
|
2 major flow types in streams |
LAMINAR- no mixing
TURBULENT- mixing complex
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Streamflow |
Water has eroded & cut into the surface so there is no defined chanel
|
Rill |
Takes advantage of grav and makes a new chanel
|
2 major types of streams |
Permanent and ephemeral
|