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Geography 12 > Geo-morphology > Flashcards

Geo-morphology Flashcards

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1
Q

Where were continental glaciers in North America?

A

Canada was nearly completely covered by ice, as well as the northern part of the United States, both blanketed by the huge Laurentide Ice Sheet. Local glaciations existed in the Rocky Mountains and the Cordilleran Ice Sheet and as ice fields and ice caps in the Sierra Nevada in northern California.

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2
Q

Describe how continental glaciers move.

A

The pressure that turns snow into ice is responsible for the movement of a glacier due to the “push down” action. They move downslope in a number of directions and are not restricted to a channel or valley. They must expand because of the constant accumulation of ice and snow. Continental glaciers do not move as quickly as alpine glaciers because there is less slope and more mass involved. They move mostly by plastic flow. Plastic flow is 50 meters of ice that causes brittle ice to become like plastic.

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3
Q

What is a Drumlin?

A

Drumlin, oval or elongated hill believed to have been formed by the streamlined movement of glacial ice sheets across rock debris, or till.

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4
Q

How do drumlins indicate glacial direction?

A

The tapered end of each drumlin hill points in the direction of glacier flow.

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5
Q

What mountain formation is created at the top end of the glacier?

A

Glacial Horns

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6
Q

What deposit is left behind by an interglacial stream?

A

Glacial Till- unsorted clays, sands, silts, gravel and boulders

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7
Q

What happens when 2 glacial valleys intersect at a different height.

A

A Hanging Valley -
A hanging valley is elevated above another valley, with one end open to the valley below. There may be a cliff or steep formation where they meet. A river or stream may run through a hanging valley, forming a waterfall that enters the lower valley.

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8
Q

A cluster of 3 Cirques creates?

A

Arêtes- horn or pyramid peak. The 3 cirques erode back into a mountain.

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9
Q

Which moraine runs down the center of an alpine Glacier?

A

Medial Moraine

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10
Q

What is the source of moraine material?

A

Glacial till- unsorted debris- rocks, gravel, sand, boulder…

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11
Q

Which moraine is deposited at the sides of Glaciers?

A

Lateral Moraines

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12
Q

What happens to glacial debris many years after a Continental Glacier melts?

A

Moraines are left behind- small hills of debris(marks end of the glacier or the lateral path it took down the valley). Large amounts of sand and gravel, which were eroded from the mountainsides, are also left behind. ??? I think?

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13
Q

What do average global temperature ice ages require?

A

In fact, the difference between today’s average global temperature and the average global temperature during the last Ice Age is only about 5 degrees. Maybe 10 degrees Celsius during the ice age, 14.2 now?

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14
Q

What is basal slip?

A

Water acts as a hydraulic jack and lubricant allowing slipping along the ground (causes movement of glaciers)

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15
Q

What is Rock Flour?

A

Rock flour, or glacial flour, consists of fine-grained, silt-sized particles of rock, generated by mechanical grinding of bedrock by glacial erosion or by artificial grinding to a similar size.

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16
Q

What shape is a glacial valley?

A

U-shaped

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17
Q

What creates glacial till?

A

Till is derived from the erosion and entrainment of material by the moving ice of a glacier. It is deposited some distance down-ice to form terminal, lateral, medial and ground moraines. Short form: it is created by the moving of a glacier and the pushing forward of unsorted material and silt.

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18
Q

How does snow become ice?

A

Snow accumulates, then snow changes due to exposed elements, recrystallizing into sand-like snow (Firn/neve) then the pressure (50 m thick) from the weight will fuse the firn together into a solid mass forming ice.

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19
Q

What makes a glacier stationary?

A

The terminus of a glacier is stationary when accumulation (snow) at the top of the glacier is equal to ablation (melt) at the bottom of the glacier- Ice/Snow Balance Budgets.

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20
Q

What is a large, misplaced rock called that is left behind after a glacier has receded?

A

An Erratic

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21
Q

Which moraine is left behind at the furthest point of a glaciers progress?

A

Terminal Moraine

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22
Q

A truncated spur involves a glacial valley cutting perpendicular to a river valley. True or False?

A

True

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23
Q

Describe a Roche Mountonnee.

A

A roche moutonnée is a rock hill shaped by the passage of ice to give a smooth up-ice side and a rough, plucked and cliff-girt surface on the down-ice side. The upstream surface is often marked with striations.

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24
Q

Describes a Permafrost landscape.

A

Permafrost is soil, rock or sediment that is frozen for more than 2 years in a row. Permafrost forms in climates where the annual air temp is 0 °C or colder. Usually in the arctic, sub-arctic and Antarctic areas.

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25
Q

What causes a Pingo?

A

Pingos are created in a permafrost area when the pressure of freezing groundwater pushes up a layer of frozen ground. Pressure (pressure that forces groundwater to the surface without pumping) builds up under the permafrost layer, and, as the water rises, pushing up the overlying material, it freezes in a lens shape.

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26
Q

What are negative economic effects of Frost Heaving?

A

Frost heaving= upwards swelling of soil during freezing conditions. Above ground pipelines can get deformed due to frost heaving. Also Frost heaving can cause many issues to agriculture due to the amount of ice in the soil.

27
Q

When glaciers melt what does the lithosphere do?

A

Isostatic Rebound causes the recently-suppressed land to bounce back up at varying speeds, sometimes deforming the land without a weight to cause an indentation.

28
Q

How much precipitation do Arid areas get annually?

A

2-3 rainfalls a year. (No more than 25 cm of rain a year.)

29
Q

Where are most deserts located?

A

Many deserts are found in bands along 30 degrees latitude north and 30 degrees latitude south (between the red lines on the map). Some deserts located by mountains and are caused by the “rainshadow” effect.

30
Q

What is common to all desert shapes?

A

The one thing all deserts have in common is that they are all arid (Dry)

31
Q

Describe a Brachan Dune

A

Barchan dunes form where there isn’t very much sand and the wind blows in one direction. These dunes are also called crescent dunes. The tips of the crescents point downwind. Transverse dunes form where there is a lot of sand and the wind blows in one direction.

32
Q

What is the role of an obstruction on these last 2 dunes?

A

?? When the wind that is blowing sand along the ground encounters an obstruction like a boulder or a bush, its forward energy is decreased and some of the sand comes to rest. The resulting heap of sand enlarges the obstruction and a dune begins to grow.

33
Q

Describe the events that build Arroyos

A

Arroyos are indicative of a river that formerly coursed through the area that is presently dry. Sometimes there are shrubs or bushes along the edges of arroyos that point to a possible underground water source. Most arroyos form as a result of flash-flooding in areas that do not get regular rainfall such as deserts.

34
Q

Describe the relationship between wind speed and erosion.

A

Wind picks up and transports particles of different sizes. Wind blows small particles away. As a result, the ground surface gets lower and rockier; this is called deflation. The rocks that are left are called desert pavement. Wind can also scour and polish rocks and other surfaces. Wind-blown sand may carve rocks into interesting shapes (abrasion).

35
Q

What causes an Oasis?

A

Oases can be naturally formed or man-made and their water sources can spring from a few places. An oasis can be formed by an underground aquifer or river that creates enough pressure for water to seep to the surface, forming the oasis.

36
Q

What is a Playa?

A

They are dry lake beds that fill with water after a storm and have large deposits of fine silt and clay. As water evaporates large amounts of soluble salts are left behind creating a salt pan. They are usually found in deserts.

37
Q

How can you tell the wind direction by looking at Yardangs?

A

Yardangs typically have a tall, steep side facing the prevailing wind direction and slope gently down away from the wind. In this way, you can determine which direction in which the wind usually blows.

38
Q

What is the primary agent of erosion in a desert?

A

Water- physical mechanical weathering

39
Q

What are rain shadow deserts?

A

All of the precipitation in the sky falls on the windward side and when it blows down the leeward side it is dry, causing a desert landscape to form.

40
Q

What is Eolian erosion?

A

Erosion and action by the wind. Winds erode, transport, and deposit materials, and are effective agents of erosion in regions with sparse vegetation.

41
Q

What is a Ventifact?

A

A ventifact is a rock that has been abraded, pitted, etched, grooved or polished by wind-driven sand or ice crystals.

42
Q

What causes a dune to migrate?

A

Wind causes a dune to migrate

43
Q

What causes deserts to expand?

A

Desertification is caused by a variety of factors, such as climate change and human activities. It is a natural process but is being sped up by these artificial factors.

44
Q

How does removing trees contribute to desertification?

A

Trees’ roots hold the soil together. Once they are lost, the soil becomes loose.
After that, if the soil becomes loose, then the top layer of the soil might get washed away or get blown with the wind. This top layer contains essential nutrients for plants to grow.
If there are no nutrients, the soil will become infertile and therefore no plants will grow, allowing for desertification.

45
Q

How does salt become a problem in arid areas?

A

The soil or water becomes too salty as evaporation reduces the volume of the mass (water, land, soil, etc) and leaves it with a more intense concentration of saltiness. This can cause infertile soil or toxic water that few fish can live in.

46
Q

What is wave refraction?

A

The bending of waves around the headland. Headland= Sides of the bays that are projected into the ocean.

47
Q

What is Fetch?

A

Fetch, an area of ocean or lake surface over which the wind blows in an essentially constant direction, thus generating waves.

48
Q

Why is Fetch important?

A

Fetch is important because it’s a major factor in the formation, size, and power of waves.

49
Q

What protects bays from future inland erosion?

A

As waves hit the shoreline over time they erode it and push it further inland. … The headland receives most of the waves’ energy and consequently protects the bay from erosion. Artificial headlands are sometimes created for this purpose: to prevent coastal erosion.

50
Q

What is a Spit?

A

A spit is an extended stretch of beach material (sand) that projects out to sea and is joined to the mainland at one end. Caused by deposition.

51
Q

What is a Tombolo?

A

A tombolo is a coastal formation that appears to be a small island that has not fully separated from the mainland. This island-like landform is actually attached to the coast by a thin sandbar or spit.

52
Q

What causes Longshore Drift?

A

Prevailing wind causes waves to approach the coast at an angle. The wind carries the sand and pebbles up the beach at the same angle as the waves. The backwash carries the material back down the beach in a steeply causing sand to disappear.

53
Q

What can stop Longshore drift?

A

A wooden barrier built at right angles to the beach. Prevents the movement of beach material along the coast by longshore drift.

54
Q

What is an economic problem with Longshore drift?

A

??? It erodes the land and therefore can decrease the value of certain properties along the coast.

55
Q

What are common features of an Emergent Coast?

A

Emergent coasts have rocky coastlines with cliffs and nearly flat platforms that extend inland where older coastal plains have been tectonically raised and are now elevated above the modern land and water interface.

56
Q

What type of Submergent coastline is created by river valleys?

A

Ria Coastline

57
Q

What causes emergent coasts?

A

Emergent coasts are a result of local tectonic uplift of the land surface or a fall in the elevation of sea level because of a reduction in the water volume of ocean basins.

58
Q

How do waves make seasonal differences to beaches?

A

Storms and wave heights (along with a general change in wave and wind direction) increase during the fall and winter months, beach berms and sometimes the dunes erode in response, lowering the beach as sand is pulled offshore from the upper portions of the beach and deposited in protective offshore sandbars. The result is typically a flatter, more concave beach shape. In the late spring and early summer months, smaller, calmer waves dominate, and sand slowly returns to the beach and berm, and the beach and dunes typically recover, as long as sediment is not lost offshore.

59
Q

What causes the majority of all waves?

A

Waves are most commonly caused by wind. Wind-driven waves, or surface waves, are created by the friction between wind and surface water. As the wind blows across the surface of the ocean or a lake, the continual disturbance creates a wave crest. … The gravitational pull of the sun and moon on the earth also causes waves.

60
Q

What type of Delta has a large tidal flats area?

A

Estuarine Deltas (tide-dominated)

61
Q

What is the dominant force in a Birds foot delta?

A

High tides and strong tidal currents

62
Q

What dominates in an Arcuate Delta?

A

Wave Dominated

63
Q

What type of tide has the earth, sun, and moon in alignment?

A

Spring Tides- occurs twice a month.

64
Q

What type of tide has the sun and moon at right angles to each other?

A

Neap Tides

Geography 12 (2 decks)

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