Final Exam Review Pt 1 Flashcards
talik
Unfrozen ground that may occur above, below, or within a body of discontinuous permafrost OR beneath a water body in the continuos region. They form connections between the active layer and the groundwater.
lacustrine deposits
The drier periods between pluvials, called interpluvials, are marekd by lacustrine deposits.
paleolakes
Ancient lakes (also known as pluvial lakes)-
ice age
A term applied to any extended period of cold (not a single, brief cold spell). It includes one or more glacials, interrupted by a brief warm spell known as interglacials.
Patterned Ground
The expansion and contraction of frost action makes soil particles, stones and small boulders move.
Ground Ice
Frozen subsurface water
Active Layer
The active layer is the zone of seasonally frozen ground that exists between the subsurface permafrost layer and the ground surface. Higher temperatures increase the thickness of the active layer. Cold temperatures increase permafrost depth and reduce the active layer.
What latitudes will you find periglacial climates?
Either high latitude (tundra and boreal forest environments) or at high elevation in lower-latitude mountains (alpine environments).
Define periglacial and list three periglacial processes.
Periglacial refers to the frost weathering and freeze thaw. They have a near-permanent ice cover or at a high elevation and are seasonally snow free Three periglacial processes are permafrost, frost action, and ground ice.
What are the two categories of permafrost?
Periglacial refers to the frost weathering and freeze thaw. They have a near-permanent ice cover or at a high elevation and are seasonally snow free Three periglacial processes are permafrost, frost action, and ground ice.
Permafrost
Develops when soil or rock temperatures remain below freezing for at least two years. Two factors that contribute to permafost: the presence of fossil permafrost and snow on the surface that inhibits heating.
Drumlin
One of two types of streamlined hills. Deposited till that was streamlined in the direction of continental ice movement, blunt end upstream and tapered end downstream.
Roche Moutonnee
One of two types of stremlined hills. Its an asymmetrical hill of exposed bedrock. It slopes gently upstream and downside it is steep.
Kame
Another feature of an outwash plain, a small hill or mound of poorly sorted sand and gravel that is deposited directly by water or by ice in crevasses or in ice-caused indentations in the surface. ]
Kettle
Sometimes a block of ice remains after the glacier has retreated. As it melts, material continues to surround the melting ice block. A kettle is what is left over; a steep-sided hole.
Esker
A curving, narrow ridge of coarse sand and gravel. It forms along the channel of a meltwater stream that flows beneath a glacier, in an ice tunnel, or between ice walls. When a glacier retreats, the esker is left behind.
Outwash Plains
Beyond the morainal deposits, stratified drift, with stream channels that are meltwater-fed, braided, and overloaded with sorted and deposited materials.
Till Plain
A till plain forms behind an end moraine; it features instratified coarse till, has low and rolling relief, and a deranged drainage pattern.
Terminal Moraine
Formed when eroded depris is dropped at the glacier’s farthest extent.
Medial Moraine
When two lateral moraines join, they form a medial moraine.
Lateral Moraine
forms along each side of a glacier.
Name and describe the three types of moraines.
Lateral, medial and terminal moraines.
Moraines
Landforms created by the deposition of glacial sediment.
Till
Unsorted debris deposited on the ground surface as a glacier flows to a lower elevation.
Stratified Drift
Sediments deposited by glacial meltwater are sorted by size and are stratified drift.
Glacial Drift
The general term for all glacial deposits, both unsorted and sorted.
What are four features of alpine glaciers?
Aretes, col, horn, tarn, paternoster lakes, fjords
Fjord
As the glacier retreats, the trough floods and forms a deep fjord in which the sea extends inland, filling the lower reaches of the steep sided valley.
Paternoster Lakes
Small, circular, stair-stepped lakes, named for their resemblance to prayer beads.
Tarn
Small mountain lakes in the cirques where the valley glaciers originated.
Horn
A pyramidal peak that results when several cirque glaciers gouge an individual mountain summit from all sides .
Col
Two eroding cirques may reduce an arete to a saddle like depression or pass, forming a col.
Aretes
Knife-edge ridges that form as cirque walls erode away, divide adjacent cirque basins.
Abrasion
When glaciers move, they pick up rocks that become embedded in the basal layer, which scour through abrasion and sandpaper the landscape, leaving behind a smooth surface.
Glacier Surge
When glaciers lurch forward without warning. Glaciers are surging overall (there is a doubling of ice-mass loss, so water works its way to the basal layer, lubricating underlying soft beds of clay)
Crevasses
A flowing alpine glacier or an ice stream in a continental glacier can develop vertical cracks known as crevasses.
Basal slip
The base movement of a glacier, much less rapid than the internal plastic flow of the glacier, so the upper portion of the glacier flows ahead of the lower portion.
What does it mean to say that a glacier is plastic?
Glaciers are pliable; they distort and flow in its lower portions in response to weight and pressure form above and the degree of the slope below.
Ablation
At the end of the glacer, its reduced in size through ablation, the collection of several process– melting (internally, surface and base), ice removal by deflation (wind), calving of ice blocks, and sublimation (the direct evaporation of ice).
Firn line
Snowfall and other moisture in the accumulation zone feed the glacier’s upper reaches. This area ends at the firn line, indicating where the winter snow and ice accumulation survived the melting season.
Glacial Ice
Analagous to metamorphic processes: Sediments (snow and firn) are pressured and recrystallized into a dense metamorphic rock (glacial ice).
Firn
In the transition step to glacial ice, snow becomes firn, which has a compact, granular texture.
What is a glacier’s mass budget?
Consists of net gains or losses of the glacial ice, which determines whether the galcier expands or retreats. Glaciers grow when its cold with lots of precipitation, it gets smaller when it has a negative net balance. Note: gravity moves glaciers forward even though its lower terminus might be in retreat owing to ablation.
How are glaciers formed?
Compaction, recrystallization and growth of snow and water. The essential input is snow that accumlates in a snowfield, a glacier’s accumulation zone. As snow accumulates, the increasing thickness results in greater pressure on underlying ice. Rain and snow melt, contribute water, and then freeze. Air spaces condense as snow is packed to a greater density. Ice recrystallizes and consolidates under pressure.
Ice Field
Not extensive enough to form the dome of an ice cap; it extends in an elongated pattern in a mountainous region.
Ice Cap
A roughly circular, covers an area of less than 50,000 km. It buries the underlying landscape completely.
Ice Sheet
The most extensive form of continental glacierl most of the Earth’s ice exists in the ice sheets that blanket Antarctica and Greenland.
Continental Glacier
A continuous mass of ice, much larger than individual alpine glaciers.
Icebergs
Pieces of floating ice, resulting from tidal glaciers that calve into the sea.
Piedmont Glacier
Wherever several valley glaciers pour out of their confining vallies and coalesce at the base of a mountain range, a piedmont glacier is formed and spreads freely over the lowlands.
Cirque
A bowl-shaped erosional landform called a cirque, which contains snowfields. A glacier that forms in a cirque is called a cirque clacier. Cirque glaciers may also feed valley glaciers.
Snowfield
The area of origin of an apline glacier;it is confined in a cirque
Alpine Glacier
A glacier in a mountain range. If its an alpine glacier in a valley, then it’s a valley glacier.
Valley Glacier
An alpine glacier found in a valley
Snowline
The lowest elevation where snow can survive year-round;it is the lowest line where winter snow persists in summer.
Glacier
A large mass of ice resting on land or floating as an ice shelf in the sea adjacent to land. Glaciers cover 11% of land (down from 30% of continental land).
Cryosphere
The portion of the hydrosphere and groundwater that is perennially frozen, generally at high latitudes and elevations. It is in a state of dramatic change as glaciers and ice melt.
