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
3) Feldspars
4) Quartz
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
Parent Material
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
Terrestrial Biomass
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
78% precipitation
What percentage of evaporation and precipitation take place over land
14% evaporation
22% precipitation
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
Q=(average depth)(velocity)(width)
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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