Glossary of Geography Unit 3
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- Definition of Weathering
- The breakdown of rock in place (bedrock) or rock fragments in soils.
- Two types of weathering
- Definition of Physical Weathering, and examples
- The physical breakdown of rock under stress; Some causes are: frost action, salt crystal growth, rapid heating and cooling.
- Definition of Chemical Weathering, and examples
- Chemical reactions that change the chemical and mineral composition of weathering rock, occurs when rock is in contact with water (especially acidic water)
- Reaction for "formation of acidity" from water and Carbon dioxide
- 2H2O + 2CO2-> 2H+ +2HCO3-
- Weathering of Feldspar containing calcium
- Feldspar + 2H+ + 2HCO3- -> Ca2+ + 2HCO3- + Clay
- Formation of calcite in the ocean from calcium ions and hydrogen carbonate.
- Ca2+ + 2HCO3- -> CaCO3 HCO3- + H+
- Formation of Carbon dioxide from calcite and hydrogen carbonate
- 2CaCO3 + HCO3- H+ -> CaCO3 + CO2 + H2O
- How does silicate mineral weathering deplete CO2 content in the atmosphere
- the reaction to form acidity in water requires two parts CO2, while only one part CO2 is given off in the formation of calcite
- Climates that favor rapid chemical weathering
- high precipitation, high temperatures
- Relative rates of common mineral weathering
1) Dolomite, Calcite
2) Mafic Minerals
- How are quartz veins formed?
- In warm areas dolomite, calcite, mafic minerals, and feldspars are removed leaving quartz veins in clay minerals (this causes weathering of quartz to almost stop)
- Weathering process
- -Initially fast weathering
-Much slower weathering when all of the easily depeted minerals are gone
-In order to continue weathering clay minerals need to be gotten rid of to expose the more easily weathered rocks. (this occurs at collission zones, mountain formation)
- How is mountain building related to Carbon dioxide
- Mountain uplift-> Rapid erosion-> fresh, easily weathered minerals exposed-> increased weathering causes a decrease in atmospheric CO2 content.
- Why did the carbon dioxide levels in the atmosphere decrease about 20-30 million years ago to the level we see today?
- Uplifting of the Himalaya Mountains and the Tibetan Plateau
- How is CO2 released back into the atmosphere from the ocean floor?
- It is released at subduction zones where a plate is melted and volcanic activity releases CO2 into the atmosphere.
- What is the russian soil called
- What distinguishes soil horizons from each other?
- Color, texture and structure
- What is Texture?
- The proportion of sand, silt and clay in the soil.
- What is structure?
- the shape, size, and strength of aggregates of soil (peds)
- Factors that influence soil formation
- Processes that form soil horizons
- Biological (roots, burrows, earthworms), Accumulation of Organic matter (produced by organic matter, added to soil), Weathering and Clay mineral formation.
- How is clay (and other materials) transported from one horizon to another
- Water flow, clay moves most in wet environments, not freezing
- How and where is calcite formed in soil?
- it is most common in dry climates, it is formed when water dries leaving ions behind.
- What is the dark colored organic matter that is generally at the top of a soil profile called?
- Pools of Carbon (largest to smallest)
- Sedimentary Rocks
- What form is most of the oceanic carbon in?
- dissolved carbon dioxide, there is slightly more going into the pool than out of.
- GLobal warming and dissolved carbon dioxide feedback
- Global warming-> warmer oceans-> warmer water holds less carbon dioxide-> ocean pool shrinks
- Where are soil decomposers most effective?
- high temperatures, soils with abundant oxyen supply (O2 supply is low in wet soil), rising temperatures in high latitudes, may cause soil organic matter to decompose
- Why does plowing fields increase CO2?
- it supplies oxygen to the soil and allows decomposition rate to increase.
- What percentage of evaporation and precipitation take place over the ocean?
- 86% evaporation
- What percentage of evaporation and precipitation take place over land
- 14% evaporation
- What percent of water does runoff and ground water make up
- movement of water into the soil
- surface runoff
- water flow over the soil surface into streams
- the sum of evaporation of water from the soil to the atmosphere and transpiration (water evaporated from plant's leaves, which they got from the soil)
- What are the openings in plants leaves called?
- What soil texture allows the most water flow when soil is wet?
- What soil structure allows the most water flow when the soil is wet
- large aggregates
- Explain the soil drying process
- larger pores lose water first
- What stage does usable water come from
- the middle stage between the wilting point and field capacity.
- Where do high infiltration rates occur
- sandy soils without a B horizon that have well developed structure at the surface.
- Explain raindrop impact
- when raindrops hit the soil surface they break down the surface aggregates and eventually a surface seal is creates, this greatly reduces the infiltration rate
- What minimizes effects of raindrop impact?
- Dense vegetation cover
leaf litter on surface
strong structure (favored by high organic matter content)
- What are the two types of soil erosion by water?
- Rainsplash- direct effects of raindrop impact (pedistal stones)
Slopewash- soil removed by surface runoff usually enhanced by rainsplash. (produces rills and gullies)
- Sediment yield
- amount of sediment supplied to streams from a given area of the land surfac in a given period of dime
- Stream Discharge (Q)
- The volume of water passing by a stream channel point in a given period of time
- The last ice age in Wisconsin
- The ice sheet that covered Wisconsin
- Laurentide Ice Sheet
- What was the last glaciation period in Wisconsin and when was it?
- The Wisconsin Glaciation reached its max about 14000 yrs. ago
- What is the time period of the last 14000 yrs. know as?
- hill that was shaped by a moving glacier, they are steamlined and look like teardrops
- pointed hills that form from sediment dropped off of glaciers
- a round hole in the ground that was formed when a chunk of ice fell of of a glacier and melted
- a river deposit formed inside of a glacier, these snaking hills of sediment can be miles long
- Terminal Morraine
- a pile of sediment at the farthest extent of the zone of ablation (accumulation)
- Recessional morraine
- piles of sediment formed by temporary glacier retreats
- a plot of discharge vs. time
- Describe the sources of low discharge patterns and high discharge patterns
- Low Discharge- groundwater discharge
High Discharge- groundwater discharge + surface runoff
- Meandering Channel
- a stream that is made up of a single sinuous channel. They usually grow and migrate down stream until they are cutoff
- Braided Channel
- Multiple channels, less sinuous than meandering streams
- Flood Plain - his definition vs. legal definition
- His: the area near a stream that is actively shaped by stream erosion and deposition
Legal: the area predicted to be covered by a floow with the 100 year recurrence interval.
- When a stream erodes downwards lowering the elevation of its channel
- Stream fills a valley with sediment, raising the elevation of its channel
- Benched representing former floodplains, they are evidence of aggradation or incision
- What causes aggradation and incision
- An imbalance between sediment supplied to the stream and the capacity of the stream to carry the sediment.
- What two things increase a stream's capacity to carry sediment
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