GEOG 1401 Exam 4 Terms

Glacier

An accumulation of ice affected by past or present movement

Continental glaciers

Presently found in Antarctica and Greenland

Alpine glaciers

Found in mountainous areas where conditions are right

Quaternary

period characterized by repeated glaciations and significant changes in climate and ecosystems.

Pleistocene

epoch within the Quaternary period, marked by the last ice ages and the evolution of modern humans.

Holocene

the current epoch following the last glacial period, characterized by a warmer climate and the development of human civilization.

Mass balance

the gains and losses of ice on glaciers

Zone of Accumulation

the area on a glacier where snow accumulation exceeds melting and sublimation, contributing to the glacier's mass.

Zone of Ablation

the lower portion of a glacier where melting and sublimation exceed accumulation, leading to a net loss of ice.

Plucking

where frost action takes place under the glacier. water beneath melts relatively frequently and can seep into the cracks in the rock. the water then refreezes and expands and breaks off pieces of the bedrock, which are carried away by the glacier

Scour (Abrasion)

where the rocks carried on the bottom of the glacier wear away the bedrock, acting like a large piece of sandpaper

Cirque

amphitheater shaped feature with very steep walls

Arete

where two cirques meet (with a glacier on either side) and the ridge becomes jagged

Horn

if three cirques meet, a peak forms that is also jagged

Hanging Valley

when the ice retreats and streams flow where the glaciers did, the tributaries enter the main valley somewhere up on the wall

Lateral Moraines

sediment from the side slopes is carried along the sides of the glacier

Medial Moraines

when two glaciers merge, the lateral moraines travel down the center

Drumlins

groups of low hills sometimes seen in glaciated areas and are shaped like inverted spoons and show the direction of ice movement

Kettles

if a chunk of ice stagnates while the rest of the glacier retreats, it can be surrounded by sediment so that when it does melt, it leaves a hole. these are usually filled with water to form ponds

Erratics

boulders that were transported by glaciers and deposited far from their bedrock source

Eskers

when the ice melts a long ridge can be left showing the course of of the stream

Isostatic rebound

when the ice melts, the land begins to rise

Periglacial environments

cold environments that are not continuously covered in ice

Permafrost

permanently frozen soil

Patterned ground

the rocks in soil are sorted and arranged into patterns. mostly polygons

Sea level change

where waves encounter the shoreline is determined mainly by the elevation of the water

Tides

caused primarily by the moon and the sun’s and Earth’s rotation. the water on the side of Earth closest to the moon is pulled toward the moon which forms a bulge in the ocean and this causes the sea level to rise

Spring tides

the highest tides occur every two weeks when the sun and moon align

Neap tide

one week after each spring tide the sun and moon are at right angles and the lowest tide

Uplift

tectonic forces can cause uplift of coastal land masses

Subsidence

the weight of sediment deposited offshore can be enough to cause the surrounding land to subside which lowers the coast

Wind waves

waves depend on the strength of the wind, how long it blows, and the distance they have to develop

Tsunamis

underwater earthquakes, volcanoes, and landslide generate these huge waves that are relatively low in the water but are huge when they reach the land

Wave breaking

in the open sea, waves do not interact with the bottom of the ocean, but as they approach land, they do. the water is slowed by friction and this slowing is greatest at the bottom of the wave, the top of the wave is less affected so it travels faster. the result is the wave deforms and it becomes too steep and breaks on itself

Wave refraction

as the waves begin to touch the bottom, they get slowed, but not all of the wave touches at the same time. the result is the that the waves have a bend

Beach drift

when the waves run back into the water, they go at right angles to the beach. the result is sediments zigzag down the beach

Longshore drift

as the waves break and run up on the beach, there are other waves right behind. the water cannot continue to pile up so it is moved down the beach in the direction away from the beach

Littoral drift

longshore and beach drift together

Wave cut notch

undermines the cliff and results in mass wasting

wave cut platform

is created where a cliff used to be after it retreats

Marine terraces

if the sea level drops or the land rises, these platforms can be raised above the water

Headlands

most resistant rock jutting out into the water

Arch

if the waves break through a weak spot in the headland

stacks

as the arch continues to be eroded, the top falls

Summer beach

there is ample sands supply and the waves are relatively gentle, the beach that develops is broad and has a gentle drop off under water

Winter beach

when there are bigger waves, much of the sand is eroded away and carried a short distance away from the beach and deposited into offshore bars. the beach is then much smaller and has a steep drop off into the water

Spit

where the coastline has an indentation, like a bay or a river mouth, the sand continues to travel in the same direction and builds up a projection of the beach into the water

Barrier beach

if the spit grows all the way across the indentation

Tombolo

sometimes the drift will connect an island to the mainland

Barrier islands

these islands protect the mainland coasts from attack by storm waves because waves lose their energy on these islands

Coral reefs

these are formed by the deposition of sediment and by the accumulated deposition of the calcium carbonate shells of corals and other sea creatures

Texas beaches

most Texas beaches have been eroding due to decreased sand supply from the damming of rivers and a rise of relative sea level

Submergent coast

the sea has risen relative to the land

Ria

in this situation, river valleys are frequently flooded, leaving indentations in the coastline

Fiord

if the drowned valleys were carved by glaciers

Safety factor

is measured by a slopes stability. a slope will become less stable if the resistance is decreased or if the force is increased

Decreasing slope resistance

remove the base of the slope, swelling clays that expands when it is wet and contracts when it is dry, saturating the soil with water because it reduces internal friction, removing the vegetation around the slope, frost action, earthquakes, and increasing slope angle

Increasing force

mostly done by increasing the weight of the material

Arrangement of rock layers

if the layers are parallel to the slope, then the slope is weaker than if they are perpendicular. this is because movement is more likely where two layers meet

Creep

the slowest form of mass movement where soil particles move slowly under the influence of gravity at a rate of a few millimeters or centimeters a year

Fall

when pieces of rock break off a wall and fall down

Slide

rock or soil moving downslope in a straight path

Slump

involves rotational movement and most occur in thick cohesive soils, like thick clay soil on a hillside, and usually moves from rain adding weight. the movement is generally spoon shaped with the upper surface tilting back as it moves down

Flow

sometimes called earthflows, mudflows, and debris flows. the material moves like a fluid, becoming mixed up in the process

Karst

terrain with distinct features resulting from the solution of rocks

Solution sinkholes

when water dissolves the surface of the rock creating a depression

Collapse sinkholes

when water flowing underground erodes a cavity in the rock. as the cavity gets bigger, the overlying rock or soil will eventually fall into the sinkhole

rock types involves

limestone (most common), gypsum, dolomite, and salts

Tower karst

as sinkholes grow, they can merge together to form more complicated features. after enough erosion has occurred, there may be only remnant hills left of the area between the sinkholes

Travertine deposits

the strange shapes that develop in caverns after they get above the water table and erosion ceases

Stalactites

hang down from the ceiling

Stalagmites

grow up from the floor

Elastic deformation

when the force is small, the rock is compressed, but if the stress is removed, the rock will return to its original shape

Plastic deformation

moderate stress where the rock flows slowly to a new shape and even if the stress stops, the rock keeps its new shape

Rupture

where the rock breaks

Plateau

if a region is uplifted and the force is equal over the entire area

Dome

if the uplifting force is concentrated at one place

Basin

the opposite of a dome where the area sinks

Horst

area in between rises

Graben

rock between them drops

Cuestas

layers of rock that have been tilted and each layer is exposed and these are often asymmetrical

Caprock

where rock layers are horizontal, the resistant rock can serve to protect the underlying rock layers from erosion

Mesa

flat-topped hill with a caprock exists because everything else has been eroded away around it

Butte

a very narrow mesa

Dendritic

material is relatively uniform in its resistance to erosion and the bedrock is horizontal

Radial

if there is a hill formed by the bedrock, like a volcano or a dome

Centripetal

where there is interior drainage, the streams all converge on the playa

Trellised

in areas with much folding, there will be short tributaries coming off of the ridges and larger streams in the troughs

Rectangular

some rocks are fractured in a rectangular fashion and streams develop on the fractures

Deranged

in formerly glaciated areas, there may have not been enough time for an organized drainage pattern to develop and the streams can flow in many directions and there may be many lakes in the area

Soil

the organic and inorganic material located above bedrock and capable of supporting life

Residual material

the products left over from chemical weathering, weathered bedrock that stays in place

Transported material

weathered bedrock that was weathered in a different place

Decomposers

things that eat dead plant matter

Humus

what organic matter turns into after it has been through the decomposers, and it is more stable and better able to release nutrients for plants

Texture

is the combination of particle sizes present in a soil

Cation exchange capacity

is a measure of the soil’s ability to hold nutrients and so, is a measure of the fertility of the soil

Soil pH

most crops do best in mildly acid soils. the soils here in west Texas are mildly alkaline

Soil horizons

Organic matter falls on the surface (O layer) and gets mixed with mineral matter below the surface (A layer), and its also called top soil. Percolating water and soil animals bring organic matter down into the A layer. Below the A layer is the only mineral matter

Leaching

Water moving down through the soil carries soluble minerals and clays from the E horizon to the B horizon