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EARTH SCIENCE at SPRING VALLEY HIGH SCHOOL

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UNIT III/A: SURFACE PROCESSES – WEATHERING AND EROSION

«1. Explain outgassing and the water cycle

a. ???? Outgassing is the release of gas (water vapor, carbon dioxide, nitrogen, and lesser amounts of other gases) from cooling molten rock or the interior of the Earth.
b. ???? Water vapor in the atmosphere condensed to form the oceans. Earth’s oceans formed as a result of precipitation over millions of years. The presence of an early ocean is indicated by ???? sedimentary rocks of marine origin, dating back about four billion years.
c. The ???? water cycle is the circulation of water from the surface of the Earth into the atmosphere and back again.
d. Precipitation may infiltrate the Earth’s surface, ???? runoff , or evaporate.
e. The release of water into the atmosphere by plants is called ???? transpiration .
f. Earth has continuously been recycling ???? water since the outgassing of water early in its history.

«2. Explain the movement of water through the ground

a. Less than 3 percent of Earth’s water is ???? fresh , and over two thirds of that is frozen. Most usable fresh water is ???? underground .
b. Infiltration can occur if the surface is ???? permeable and ???? unsaturated , and if the ???? slope (gradient) of the land is gentle enough.
c. The rate of ???? infiltration is determined by the porosity and permeability of the soil.
d. ???? Porosity is the percentage of open space in a sample compared with its total volume.
e. Porosity is determined by the ???? shape of the particles, how they are packed, and whether or not they are ???? sorted by size.
f. Size does not affect ???? porosity . A 1000mL container full of large beads, and a 1000mL container full of small beads both have ???? THE SAME porosity!
g. The ???? permeability of a material is a measure of the rate at which water can pass through it.
h. Permeability depends on pore ???? size and on whether or not the pores are ???? interconnected .
i. The permeability of loose materials ???? increases with increased pore size.
j. Surface ???? runoff can occur when rainfall exceeds the permeability rate, when the soil is saturated, or when the slope of the surface is too great to allow time for infiltration.
k. Water moves upward into tiny pore spaces by ???? capillary action.
l. Zone of ???? Saturation - Groundwater zone within the Earth's bedrock where all available pores spaces are filled by water; found beneath the water table.
m. Zone of Aeration- Horizontal zone that extends from the top of the water table to the ground surface; soil and rock pore spaces in this zone are ???? not saturated with water.
n. ???? Water Table - Top surface of groundwater; top of zone of saturation; the depth of the water table depends on the climate, season, and location.
o. For a well to be productive, it must extend down below the ???? water table to the zone of saturation.

«3. Compare and contrast methods of physical and chemical weathering

a. ???? Weathering is the physical or chemical breakdown of rocks.
b. Weathering occurs when the ???? lithosphere (rocks) is exposed to the ???? atmosphere (air) and the ???? hydrosphere (water).
c. ???? Physical weathering causes a rock to crack or break into pieces.
d. Physical weathering may occur as the result of alternate freezing and melting of ???? water (frost action), when plant roots widen cracks (plant action), and when the pressure of overlying material is ???? removed (pressure unloading/exfoliation).
e. Chemical weathering changes the chemical ???? composition of the minerals in rocks, usually weakening the rock.
f. Chemical weathering may occur when minerals react with ???? oxygen (oxidation), ???? carbonic acid (carbonation), and ???? water (hydrolysis).

«4. List the end products of weathering

a. ???? Weathering breaks down rocks into particles of many sizes (clay, silt, sand, pebbles, cobbles, boulders)
b. ???? Soil is a mixture of rock and organic material ( ???? humus ).
c. Soils are the result of weathering and ???? biological activity over long periods of time.
d. A mature soil ???? profile shows three distinct horizons. The A-horizon ( ???? topsoil ) is dark and rich in humus. The B-horizon ( ???? subsoil ) is lighter in color, has more clay, and less humus. The ???? C-horizon is made of slightly weathered bedrock (rock fragments). Beneath the three horizons is the unweathered ???? bedrock .
e. Soils may be ???? residual (form from underlying bedrock) or ???? transported (form from sediments that have been carried from some other place).

«5. Explain how different climates, particle sizes and composition & exposure affect weathering processes

a. At high latitudes and high altitudes, where it is ???? cold and humid, frost action is the major form of weathering.
b. In warm and humid climates ???? chemical weathering is most important.
c. In ???? arid (dry) climates, very little weathering takes place.
d. Local climatic conditions (winds, nearness to cities, etc.) can affect the ???? rate of weathering.
e. Small rock particles will weather faster than a single large sample of the same mass because more ???? surface area is exposed by the small particles.
f. Rocks containing more ???? resistant minerals will weather at a slower rate.
g. Rocks that are not exposed to the atmosphere and hydrosphere will weather at the ???? slowest rate.

«6. Define and list the agents of erosion

a. ???? Erosion is the movement of sediments from one place to another.
b. Whatever is moving sediments is an ???? agent of erosion.
c. Most sediments on Earth are ???? transported (have been moved).
d. ???? Running water is by far the most important agent of erosion.
e. Minor agents are glaciers, the wind, and ???? waves breaking against the coast.
f. ???? Gravity may act alone as an agent of erosion.

«7. Understand the importance of gravity in erosional/depositional systems and give examples

a. ???? Gravity is the main driving force of erosion.
b. ???? Mass Movement- General term that describes the downslope movement of sediment, soil, and rock material.
c. Landslides- a general term for the downslope movement of sediments under the influence of ???? Gravity .
d. Slumping- the downslope movement of material on a curved slip surface.
e. Hillside creep- the slow movement of sediments downslope under the influence of gravity.

«8. Explain the mechanism of wind erosion /deposition

a. Erosion of sediments by wind is most common in ???? arid climates and along shorelines.
b. ???? Wind- generated features include dunes and sand-blasted bedrock.
c. Wind can transport sediment the size of ???? sand or smaller.
d. Wind can create features like sand dunes in ???? deserts and on ???? beaches . Sand dunes are steeper on the ???? leeward side.
e. Dunes ???? migrate as sand from the windward side blows over to the leeward side.
f. Sediments eroded by ???? wind are often rounded, and under magnification, have frosted surfaces.
g. Wind-deposited sediments usually consist of well-sorted, small particles in ???? layers that may be tilted.
h. Cross-bedding may develop when ???? sediments are deposited by the wind in leaning positions on sand dunes.

«9. Explain the mechanism of erosion & deposition by ocean waves and currents

a. Wave action has erosional affects on shoreline rocks and on ???? beaches .
b. Most ???? waves result from winds.
c. Swash- motion of water ???? up the beach
d. Backwash- motion of the water running back ???? down the beach
e. Longshore current- a current that flows ???? parallel to the shoreline, caused by waves moving towards the beach at an angle.
f. Longshore Drift- The movement and deposition of coastal sediments ???? parallel to the beach because of longshore currents.
g. Rip currents- strong surface currents that flow ???? away from the beach.
h. ???? Density currents result when water in an area of the ocean has become denser than the water around it. The denser water moves beneath the less dense water forming a ???? current .
i. Sandbar- a bar of ???? sand formed by ocean currents depositing sand near the shore.
j. ???? spit - A long and narrow accumulation of sand and/or gravel that projects into a body of ocean water, attached at one end to the beach.
k. Baymouth bar- a narrow deposit of sand and/or gravel found across the mouth of a ???? bay .
l. Hook- A spit with a ???? curved end.
m. Barrier island- a narrow, sandy coastal island built through wave action and ???? separated from the mainland. Such islands form a barrier that protects the shore from the open sea. They are easily flooded during storms or high water, and are constantly in the process of being created, shifted, or destroyed by wind and ???? waves .

«10. Recognize features of erosional/depositional systems.

a. You should be able to identify the agent of erosion responsible for the formation of the features listed above (dunes, spits, etc.).
b. In certain erosional situations, loss of property, personal injury, and loss of life can be ???? reduced by effective emergency preparedness.