Geology Lab Final Flashcards
(50 cards)
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)
