Geology Lab Final Flashcards
Hydrologic cycle
Atmosphere, biosphere and the solid earth. Water evaporates from oceans into atmosphere, precipitated and flows into rivers and underground waters back to the seas. High altitude and latitude precipitation’s water can become part of a glacier and be stores as glacial ice for tens to thousands of years before returning to the sea t
What are glaciers?
A thick mass of ice originating on land from the compaction and recrystallization of snow that shows evidence if past and present flow (movement)
Two basic cycles: hydrologic cycle and rock cycle
Rock cycle
Water as glacial ice is a powerful erosional tool and erosion plays an important part in the rock cycle
Alpine (valley) types of glacier
Glaciers in a mountain valley, which may have been Previously a stream valley. Unlike rivers they flow only a few cm per day. They can be long, short, wide or narrow. They aye be single or have branching tributaries.
Ice Sheets (Continental Ice Sheets) type of Glaciers
Much larger in scale because of the low solar radiation at the poles makes these regions eligible for massive ice accumulation. There were many ice sheets in the past but now only two remain. Greenland and Antarctic
Antarctic ice sheet
South Pole- as much as 14,000 feet thick and 5.5 million sq. miles
Ice caps
Also completely bury underlying landscapes but on a much smaller scale than ice sheets. Example: parts of Iceland and large islands in the Arctic Ocean
Outlet Glaciers
A tongue of ice normally flowing rapidly outward from an ice cap or ice sheet from mountain areas to the sea
Piedmont Glacier
Occurs when steep valley glaciers spill into relatively flat plains.
Widens onto a lowland.
Firn
Granular recrystallized snow. A translational stage between snow and ice.
More snow adds and pressure increases compacting the ice grains. After a depth of 160 ft the weight fuses the firn into a solid moss of interlocking crystals
Plastic flow
Movement within the ice shelf. The ice grains slip and slide past each other ex: like a conveyor belt
Basal slip
Ice mass slides over the surface below. The melted water acts as a lubricant over the rock
Ablation
Loss of ice and snow from a glacier
Zone of accumulation
The part of a glacier characterized by snow accumulation and ice formation. Outer limits is the snow line
Crevasses
A deep crack in the brittle surface of a glacier caused by ice flowing over irregular surfaces alone the zone if fracture
Glacial erratic
an ice transported boulder that was not derived from the nearby bedrock. Ex: central rock boulders
Moraines
Landforms made by glacial deposits of till
Kettle holes
Depressions created when blocks of ice become lodged on glacial deposits and the. Subsequently melt
Esker
Ridge composed largely of sand and gravel deposited by a stream flowing in a tunnel beneath a glacier near its terminus
Cirque
They are found high on mountainsides and tend to be wide rather than long. Bowl like hollows.
Normal faults
Are caused by tension (rock lengthening). As tension all stress pulls the rocks apart, gravity pulls for the hanging wall block. Hanging wall moves downward in relation to the footwall block (which doesn’t move)
Reverse fault
Are caused by compression (rock shortening). As compressional stress pushes the rocks together. One block of rock gets pushed atop another. Footwall block is unmoved and hanging wall block has moved upward
Thrust faults
Are reverse faults that develop at a very low angle and may be very difficult to recognize. Reverse faults and thrust faults place older strata on top of younger strata
Springs
Places where water flows naturally from the ground ( from spaces in the bedrock)
Disappearing streams
Streams that terminate abruptly by seeping into the ground
Tarn
A small lake in a cirque
Glacial erosion - they shape the land with many topographical features
They erode the land in two primary ways:
Plucking and Abrasion
Plucking- glacial erosion
As a glacier flows over a fracture bedrock surface is loosens and lifts blocks if rock and incorporates it into the ice
Abrasions - glacial erosion
As the ice and it’s load of rock fragments move over bedrock it works a sandpaper and polishes the scratches the rock causing strait ions and grooves, which can show you the directions of which the glacier has come from
Synclines
Are down folds or concave folds with yr youngest rocks in the middle
Anticlines
A ridge shaped fold of striated rock in which the strata slope downward from the crest
Domes and basins
Bare large somewhat circular structures formed when strata are wrapped upward, like an upside down bowl (dome) or downward like a bowl (basin)
Confining beds
Impermeable bedrock materials that prevent the flow of water. Ex: clay, mudstone, shale or dense igneous and metamorphic rock
Confined aquifers
Rock strata that conduct water, opposite of confining beds or aquitards. Ex: sandstones and limestones
Sinkholes
Surface depressions formed by the collapse of caves or other large underground void spaces
Solution valleys
Valley- like depressions formed by a linear series of sinkholes or collapse of roof of a linear cave
Alluvium
Consists if gravel, sand, silt, and clay. Sediment that is transported during erosion of land. Brought to flood plains, point bars. Channel bars, deltas and alluvial fans
Stream drainage system
The system where when it rains. Sheet flows form due to rain fall creating small streams to larger streams to large rives and then to lakes of oceans
Dendritic pattern - stream drainage patterns
Resembles the branching of a tree. Common where a stream cuts into clay lying layers of rock or sediment. Also where a stream cuts into homogeneous rock (crystalline igneous rock) or sediment (sand)
Rectangular pattern - steam drainage pattern
A network of channels with right- angle bends that form a pattern of interconnected rectangles. Developed over rocks that ate fractured or faulted in two main directions that are right angles
Beach
A gently sloping deposit of sand and gravel along the edge of shoreline
Delta
A sediment deposit at the mouth of a river where it enters an ocean or lake
Washover fan
A fan shaped deposit of sand or gravel transported and deposited landward of the beach during a storm or very high tide
Spit
A sand bat extending from the end of a branch into the mouth of an adjacent bay
Wave cut cliff
Seaward facing cliff a long a steep shoreline, produced by wave erosion
Wave cut platform
A bench or shelf at sea level or lake level along a steep shore and formed by wave erosion.
Groin
A short wall constructed perpendicular to the shoreline in order to trap sand and make build up a beach. Sand accumulated on the up-current side of te groin in relation to the long shore current
Tombolo
A sand bar that connects an island with the mainland or another island
Stack
An isolated rocky island near a headland cliff
Tied island
An island connected to the mainland or another by a tombolo
