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Geology Final Exam
Question | Answer |
---|---|
What drives the water cycle? | Solar Energy |
The areas from which streams collect water are separated into ______________, the borders of which are defined by local topographic highs. | Drainage basins |
What percentage of Earth’s surface water is fresh surface water? | About 1.2% |
When a stream enters a lake or ocean, the stream velocity slows. What would you expect to happen to the bedload and suspended load? What landform would this create? | The stream would lose energy and drop its sediments forming a delta. |
How does an oxbow lake form? | when a meander is cut off and abandoned |
Using the formula for discharge, which of these streams has the highest discharge? | A stream that is 20 feet across, 3 feet deep, and moving at 10 feet per second |
Entrenched meanders on streams like the Colorado or San Juan flowing on the Colorado Plateau in Utah are a result of? | Tectonic elevation of the Colorado Plateau |
Topographic highs typically define which of these features? | Drainage basins |
What causes braided stream channels to form? | nearby sources of coarse sediment |
What is the result of tectonic elevation of the Colorado Plateau on rivers that flow across it? | Effective lowering of base level |
Where the stream velocity increases along a cut bank, what also increases? | Erosion |
In terms of sediment transport, what are the types of load a river carries? | suspended, bed, dissolved |
What is the energy source that drives the entire hydrologic cycle? | The Sun |
What is a drainage basin? | An area that collects and drains precipitation |
Which river has the largest drainage basin in North America? | Mississippi |
The three things that determine the velocity of a stream are? | Gradient of terrain, Stream channel area, Discharge |
Which of the following types of sediment will most likely be transported by suspension? | silt and clay |
How are coarse gravel or boulders transported by streams? | Bed load |
Define what is meant by a river's CAPACITY? | Measure of the total amount of sediment a stream can carry |
What determines a river's capacity? | Discharge and flow velocity of the stream |
Define competence | Ability of a stream to transport a particular size of material |
What determines a river's competence? | Flow velocity |
What is base level? | The lowest elevation to which water can erode or flow. |
What are the two types of base level? | Local base level and Ultimate base level. |
What is local base level? | temporary limit of stream erosion |
What is ultimate base level? | the lowest elevation which a stream can reach |
What is a delta? | a location where rivers enter a large body of water that form a triangular shape as the river deposits sediments and switches course. |
Are oxbow lakes characteristic of rivers near base level or rivers that are far from base level? | Close to base level |
People try to control floods by engineering efforts such as? | Diversion canals, Levees, Dams |
Where would braided streams most likely occur? | Streams with a high sediment load and steeper slopes |
What type of drainage pattern would you expect to form on a stratovolcano? | Radical |
Streams transport 3 forms of what sediment loads? | dissolved load, suspended load, bed load |
Dissolved loads are? | carried in solution |
Suspended loads are? | carried in the water column |
Bed loads are? | carried by the stream along its bottom |
Groundwater comprises what portion of all water of the hydrosphere of planet Earth? and what portion of that is fresh water? | less than 1% of all water, but 25-30% of all fresh water on Earth |
The zone of saturation is also called? | The Phreatic zone |
The unsaturated zone is also called? | The Vadose zone |
What is the process within Earth's hydrologic (water) cycle where water enters the ground water system? | infiltration |
The boundary between the two zones is the? | Water table |
Which of the following has the highest permeability? | Gravel |
What permits ground water to flow in the subsurface? | hydraulic gradient, gravity, aquifer properties - favorable porosity and permeability. |
Clay has a high porosity but poor permeability - why? | The pore spaces are too small to allow water to travel through the rock. |
Which of the materials below would make the best aquifer? | Highly-fractured limestone |
Ground water flows parallel to groundwater contours (lines of equal subsurface groundwater elevation)? | False |
Now give an example of a good type of material for an aquitard. | Clay |
The two conditions necessary for an artesian system to exist are? | Inclined aquifer and Aquitards above and below the aquifer. |
A high density of extraction wells and aggressive pumping can? | cause cones of depression, and even intersecting cones of depression, lowering the local water table, cause some wells to go dry, and lower the regional water table. |
How much ground subsidence has occurred in San Joaquin Valley in California due to excessive groundwater removal? | 9 meters |
What accounts for the formation of large fissures in the ground in some regions of Arizona, Nevada, California and Utah? | Groundwater pumping |
Three of the most common and dangerous sources of groundwater pollution are? | Sewage, especially from old septic tanks, Landfills and abandoned fuel storage tanks, and DNAPLS (Dense Non-Aqueous Phase Liquids) like Trichloroethylene. |
What type of rock does karst topography develop upon? | Limestone |
What type of acid in solution (water) is present to dissolve limestone to form caves and sinkholes? | Carbonic |