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HUNTER / Geology / GEOL 100 / What is the meaning of weathering in geography?

What is the meaning of weathering in geography?

What is the meaning of weathering in geography?


School: Hunter College of the City University of New York
Department: Geology
Course: Intro to Geology
Professor: Faye melas
Term: Fall 2018
Cost: 50
Name: Geology 100 study guide
Description: this is a study guide for exam 2 of Geology 100. it covers material from weathering, erosion, groundwater, glaciers and the Aswan Dam Power Points.
Uploaded: 11/12/2018
8 Pages 57 Views 3 Unlocks

● 56 MC questions

What is the meaning of weathering in geography?


Weathering is the physical, chemical and biological disintegration, or breakdown of rock material, in contact with the atmosphere, lithosphere and hydrosphere

● Climate: temp and moisture characteristics

Mechanical weathering is when there is no change in the chemical composition, just the disintegration into smaller pieces

● Pressure release

● Crystallization of salt in cracks

● Thermal expansion and contraction

● Water: freeze- thaw cycles

Chemical weathering is the breakdown as a result of chemical reactions. transformation/decomposition of one mineral into another

What is the meaning of mechanical weathering in geography?

● Carbonate dissolves If you want to learn more check out What is the difference between felony and misdemeanor?

● Primary -> secondary minerals

● Acid reactions: water and carbon dioxide ← → carbonic acid, water and sulfur ← → sulfuric acid, H+ is effective at breaking down minerals

● Dissolution: the biological activity in soils generates substantial CO2 ● Oxidation: oxygen dissolved in water promotes oxidation of sulfides, ferrous oxides, native metals

● Organic activity: plant material makes H+ ions available

● Least effective in polar regions

● Most effective in areas of warm, moist climates

● Limestone and marble dissolve in carbonic acidIf you want to learn more check out What does the u-rate really measure?

Physical weathering

What is the meaning of chemical weathering in geography?

● Reduces rock material to smaller fragments that are easier to transport ● Increases the exposed surface area od fock, making it more vulnerable to further physical and chemical weathering

Solution is the process by which rock is dissolved in water.

Calcium carbonate(calcite, limestone), sodium chloride(salt), and calcium sulfate(gypsum) are particularly vulnerable to solution weathering

Karst landforms develop in areas underlain with limestone. When Lake Jackson’s sinks rupture and the lakewater drains out, the process is referred to a drawdown. Forms from the dissolution of rocks.

Saltation the movement of hard particles such as sand over an uneven surface in a turbulent flow of air or water. 

A point bar is an area of deposition whereas a cut bank is an area of erosion. River discharge is the volume of water flowing through a river channel. This is the total volume of water flowing through a channel at any given point and is measured in cubic metres per second. If you want to learn more check out Are standard deviation and standard error are the same?

The name of the largest river in North America is the mississippi. 

Velocity is what controls stream erosion and deposition. 

The things that control velocity are: 

● Slope 

● Channel roughness 

● Channel gradient 

Erosion and mass wasting

The agents of erosion are gravity, water, wind and ice

What type of erosion is gravity enforced?

● Mass wasting (slope of land is very important)

● Most stable is when it is totally horizontal

The fastest type of mass wasting is mudflow, avalanche

The types of mass wasting are:

● Slow vs. fast

● Wet vs. dry

● Cohesive vs. fragmented We also discuss several other topics like Why rehabilitation became important?

Creep the slow downslope movement of soil, sediment or rock along more gentle slopes that give rise to the more rapid forms of mass wasting. An extremely slow movement of material down slope. You can often notice bent trees on a creep.

Meander cutoffs (OXBOW LAKES) may form when a new, shorter channel is cut through the narrow neck of a meander (as during a flood).

Landslide is the sliding down of a mass of earth or rock from a mountain or cliff Slump a landslide is the sudden and rapid movement of material. California suffers landslides when the water table created slumps in mountain sides and the supporting rock becomes weak.

Earthflow is a downslope viscous flow of fine-grained materials that have been saturated with water and moves under the pull of gravityWe also discuss several other topics like Who is maxime bernier?

Mudflow involve movement of wet, more than 30% water, soil or unconsolidated, clay-rich sediment in a fluid motion. Occurs when the material within the sloped surface are saturated or nearly saturated with water. They are often confined to valleys and can be several hundred feet thick.

Debris flow similar to mudflows except that they involve soil, sediment and a significant number of boulders. They occur when high slope angles, water saturation and unconsolidated soil and sediment, and poorly consolidated rock layers combine to create an unstable situation Avalanche a mass of snow, ice, and rocks falling rapidly down a mountainside Rock fall consists of one or more rocks that detach from the high part of a steep slope, dropping and perhaps bouncing a few times as they move very rapidly down slope. They occur without warning and are very dangerous. You can usually tell where rock falls are common by identifying talus at the base of steep slopes.

In 1970 an earthquake triggered the landslide in Peru that killed 25,000 people.

Bed load is particles carried by rolling, bouncing or dragging along the stream bed (pebbles, cobbles, boulders) We also discuss several other topics like What reactions best depicts the formation of sodium chloride?

Deltas are deposits at the mouth of the river. Velocity slows when entering a large body of water. As a delta forms most of the sedimentary material is carried across the relatively flat top surface, then deposited over the edge in steeply sloping foreset beds. Finer material is

carried further out and deposited as relatively flat bottomset beds. While the delta grows the flat top aggrades and some additional material is deposited as topset beds. Over time the delta develops a cross section such as the one shown below.

Aswan Dam 

an embankment dam which means that there is a triangular shaped block of granite that holds the water back. About 600 km south of Cairo the capital of Egypt.

● Construction started on the dam in 1960 and it was completed in 1971. ● Lake Nasser was created behind the Aswan High Dam. It is the largest artificial lake in the World (560 kms in length). It is named after Gamal Abdul Nasser, the former President of Egypt.

● Control of flooding is carried out by the dam. By keeping so much water back in Lake Nasser, the River Nile rarely floods the surrounding farmland any more. ● Increased erosion in front of the dam and disposition behind it


Groundwater is the water that lies beneath the ground surface, filling the pore space between grains in bodies of sediment and rocks, and filling cracks and crevices in a;; types of rocks. The sources are rain and snow that fall to the ground. A portion percolates down into the ground to become groundwater.

Aquifer- geological materials that can store and transmit large quantities of groundwater aquiclude(aquitard)- impermeable beds (.1% porosity) that prevent groundwater movement. Porosity- % volume that is empty space

Permeability- measure of how “connected” the pore spaces are

A good aquifer has both a high porosity and permeability.

Water table: boundary between the unsaturated (vadose) zone and saturated zone of an aquifer

Cone of depression- A depression of the water table formed around a well when water is pumped out; it is shaped like an inverted cone

Artesian well- A well in which water rises above the aquifer

Stalactites- icicle-like pendants of dripstone hanging from cave ceilings, generally slender and are commonly aligned along cracks in the ceiling, which act as conduits for ground water Stalagmites- cone-shaped masses of drip-stone formed on cave floors, generally directly below stalactites

Karst Topography-is a landscape formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum.

Rain water dissolves carbonade rocks because it has calcite and the rain water has acid (carbonic acid).

The primary force that causes rocks to move down is gravity.

Some of the effects of excessive pumping water out of the ground are:

● Cone of depression

● Causes sinkholes from lowering the water table

● Substance (subsiding)


A glacier is a mass of ice that persists throughout the year.

Firn- partially compacted snow

Ice sheet- covers the major portion of a continent

An "ice age" is a generic geological period of long-term reduction in the temperature of the Earth’s surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers.

The causes of ice ages are not fully understood for both the large-scale ice ages and the smaller and flow of glacial interglacial periods within an ice age. Several factors are important, however:

1.The motion of tectonic plates resulting in changes in the relative location and amount of continental and oceanic crust on the Earth's surface, which affect wind and ocean currents.

2.Atmospheric composition (the concentrations of carbon dioxide, methane. The specific levels of these gases are now able to be seen with the new ice core samples from the Antarctic shelf over the past 650,000 years.

3.Variations in solar output.

4.The impact of relatively large meteorites.

5. Volcanism including eruptions of supervolcanoes.

6. Milankovitch cycles: Milankovitch mathematically theorized that variations in eccentricity, axial tilt, and precession of the Earth's orbit determined climatic patterns on Earth.

For the past 200 years, glaciers have been melting.

The two main types of glaciers are continental and alpine/valley.

The glacier in greenland is called continental.

The largest glacial mass today is located in antarctica. Second is Greenland. What percent of land area is covered by glaciers? 10,000 years ago was 30% and now is 10%.

What type of moraine accumulates at the middle of the glacier when two glaciers merge together? Median

What glacial landform is represented by long island southford, martha’s vineyard nantucket? Terminal moraine

When does a glacier retreat? When it melts faster than it grows

Why have researchers been interested in drilling the ice sheets in antarctica and greenland? They are looking to study past climates from the gasses trapped in the ice layers.

The shape of glacially eroded valleys are U shaped.

The last ice age peaked 10-18 thousand years age. The sea level dropped as well because the water froze.


The geological processes powered by wind are collectively called Eolian Loess- Wind-blown silt and clay transported through suspension.

The loess deposits that are found in the upper Mississippi valley, came from the deserts. The deflation surface is the depression that forms when the wind removes the smallest particles and removes the surface of the ground.

Parabolic sand dunes are what are typically found on beaches.

Desertification is the transformation of semi arid regions into deserts.

Sand and a dry climate are what is needed to create sand dunes.

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