Pg Test 2 Terms

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Weathering

Back 1

The physical breakdown (disintegration) and chemical alteration (decomposition) of rocks at or near the Earth's surface

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Mass Wasting

Back 2

the transfer of rock or soil downslope under the influence of gravity

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Erosion

Back 3

the physical removal of material by mobile agents such as water, wind, or ice

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Mechanical Weathering

Back 4

the physical breakup of rocks into smaller pieces. Afterward, the rock still exhibits characteristics of the original material. By breaking rocks into smaller pieces, more surface area is created, thus promoting chemical weathering

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Chemical Weather

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The alteration of a rock's chemistry, changing it into different substances.

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Frost Wedging

Back 6

Rock at cold temperatures, rock cracks, ice in those cracks, ice melts, exposint the crack and ice gets into the crack again, making crak even wider. As a result small pieces fall from thetop of the mountain to the bottom

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Talus Slopes

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Rocks that are broken into smaller pieces and tumble into large piles at the base of steeply sloped cliffs

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Sheeting

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a mechanical weathering process characterized by the splitting off of slab like sheets of rock.

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Exfoliation Domes

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If sheeting continues these are formed. Soil keeps going down exposing igneous rocks

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Spheroidal Weathering

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the result of the corners/edges of angular blocks becoming more rounded due to their increasedd surface area available for chemical attack

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Differential Weathering

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Masses of rock do not weather uniformly, Varying rates of weathering resulting from some rocks in an area being more resistant to weathering than others.

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Soil

Back 12

A combination of mineral and organic matter, water, and air

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Regolith

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The layer of rock and mineral fragments that nearly everywhere vocers Earth's land surface

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Parent Material

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The nature of the parent material influens soil in two ways, due to the affects of the rate of weathering. Basically, the longer the soil has been forming, the thicker it becomes and the less it looks like the parent material.

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Horizons

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O, A, E, B horizons make up solum/true soil. O + A = top soil. E horizon has a lot of water washing through this zone, taking out finer soil components "Eluviation" Water percolating downward taking inorganic soil components into deeper zones is called Leaching

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Humus

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organic matter, is decayed remains of animal life and plant life.

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Eluviation

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the washing out of fine soil components from the A horizon by downward percolating water.

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Leaching

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Water percolating downward also dissolves soluble inrganic soil components and carries them to deeper zones, This is the depletion of soluble materials rom the upper soil by doward percolating water.

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Solum

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True Soil

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Pedalfer

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Soil rich in alumina and iron and deficient in carbonates, found in and characteristic of humid regions

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Pedocal

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soil that includes a definite hardened layer of accumulated carbonates

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Laterite

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contains little or no humus. Coupled with highly leached and brick like nature of laterites makes these soils poor for growing crops

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Gullies

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Rills that continue to grow larger as a part of soil erosion

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Sheet Erosion

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Soil moved in thin sheets of water

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Rills

Back 25

After flowing as sheets for a short distance, the are the threads of currents develop tiny channels called ____

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Detrital Sedimentary Rocks

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Rocks that form from the accumulation of materials that origninate are transported as solid particles derived from both mechanical and chemical weatheing.

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Chemical sedimentary rocks

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Sedimentary rock consisting of material that was precipitated from water by either inorganic or organic means

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Sorting

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the degree of similarity in particle size in a sedimentary rock

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Well Sorted

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Indicates grains of a sandstone are relatively the same

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Poorly Sorted

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Indicates that rock has a mixture of large and small particles.

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Clastic

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a sedimentary rock texture consisting of broken fragments of preezisting rock

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Non Clastic

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A term for the texture of seedimentary rocks in which the minerals form a pattern of interlocking crystals

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Environment of deposition

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Continental, Marine, and Transitional

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Sedimentary Structures

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Strata/beds, Bedding Planes, Cross Bedding, Graded Beds, Ripple Mark, Mud Cracks, Fossil

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Strata/beds

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Most common sedimentary structure, layers of sediment that accumulate

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Bedding Planes

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Flat surfaces along which rocks tend to break, these seperate strata

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Cross Bedding

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Layers of sediment that accululate that is inclined. Characteristic of rapid deposition from water containing sediment of varying sexes such as turbidity current

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Ripple Mark

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Small waves of sand that develop on the surface of a sediment layer y moving air or water. The ridges form at right angles to the direction of motion

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Mud Cracks

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Indicates that sediment was alternately wet and dry. Associated with tidal flats, shallow lakes, and desert basins.

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Fossil

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Remains or traces of past life. Extremely important in determining geologic pasterials.

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Differential Stress

Back 41

Forces are unequal in different directions. Rocks subjected to differential stresses are being shortened in the direction pressure is being applied to and elongated in direction perpenduclar to that force

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Confining Pressure

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As rocks are buried, they experience greater pressures where forces are applied equally in all directions. At greater depts, this can cause re-crystallization. DOES NOT cause rocks to fold or deform.

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Metamorphism

Back 43

the transformation of one rock into another and are produced from preezisting igneous, sedimentary, or other metamorphic rocks.

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Rock Cleavage

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Closely spaced planar surfaces along which rock split into thin, tabular sheets when hit by a hammer. Can develop in low grad metamorphic conditions

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Slaty Cleavage

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the most developed rock cleavage. Best displayed in slates

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Schistosity

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type of foliation, Under extreme conditions, the minerals in the slate (micas and chlorite) may begin to grow large enough to see with the eye

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Types of Foliation

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Rock or Salty Cleavage, Shistosity, Gneissic Texture

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Foliation

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refers to any planar arrangement of mineral grains or structural features within a rock.

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Nonfoliated

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Metamorphic rocks not exhibiting foliation

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Porphyoblastic texture

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Non foliated, consists of large grains (called porphyoblasts_ that are surrounded by a fine-grained matrix of other minerals

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Aureole

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This forms a zone of alteration surrounding the magma body which can be relatively small or several kilometers thick, depending on the size of the magma body

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Index minerals

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Good indicators of the metamorphic enviornment in which they form

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Migmatites

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Under the most extreme temperature conditions, rock may begin to melt. When rocks contain light bands of igneous minerals and dark bands of metamorphic minerals this is the result. These rocks technically don't belong in either igneous, metamorphic, or sedimentary rock.

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Liquefaction

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During intense earthquakes, water can saturate surface material causing them to lose their strength and behave as fluid like mass. observed in 1964 Good Friday earthquake

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Rock Avalanche

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The events described in Peru had movements of material as fast as 125 miles per hour

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Slump

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refers to the downward sliding of a mass of rock or unconsolidated material moving as a unit along a curved surface Mass wasting event

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Rockslides

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Sudden and rapid movements that occur when detached segments of bedrock break loose and slide downslope

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Debris Flow

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the relatively rapid type of mass wsting process that involves a flow of soil and regolith containing a large amount of water. Also called mudflows and lahars

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Lahar

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Mass wasting event, known as debris flow

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Earthflow

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these most often occur on hillsides in humid areas during times of extremely heavy precipitation of snowmelt. Mass wasting event

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Creep

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this involves the gradual downhill movement of soil and regolith primarily caused by the alternate expansion and contraction of material caused by wetting/drying or freezing/thawing

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Solifuction

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occurs in regions underlain by perma frost. This form of creep occurs in a zone above the permafrost called the active layer which is characterized by alternate freezing and thawing during seasonal changes.

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Permafrost

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Permanently frozen soil.

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Effects of Permafrost

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when water and soil are both frozen nothing happens. When water heats up, soil starts to melt a little, and the rock moves upward. When water freezes again the rock moves back down.