Exam 4 study guide Geo

desert pavement

- Smoothy weathered, vanish - like surface of closely packed pebbles that has developed on the upper part of an alluvial fan or bajada, where the stable land surface is no longer subject to stream deposition. (47)

horns (dunes) -

A barchan dune is also sometimes referred to as a crescentic dune, is a U-shaped type of sand dune that consists of horns or tips that point downwind or against the wind. Sand supply is abundant where barchans occur along with a hard ground and a constant wind direction. (?)

horns (glaciers) -

A horn results when glaciers erode three or more arêtes, usually forming a sharp-edged peak. Cirques are concave, circular basins carved by the base of a glacier as it erodes the landscape. (?)

Talik

A talik is a layer of year-round unfrozen ground that lies in permafrost areas. ... Sometimes closed, open and through talik are distinguished. -an unfrozen zone below a body of unfrozen water but above the permafrost

Iceberg

An iceberg or ice mountain is a large piece of freshwater ice that has broken off a glacier or an ice shelf and is floating freely in open water. It may subsequently become frozen into pack ice (one form of sea ice).

Lake waves

As with ocean surfing, ideal wave conditions are when the wind switches offshore. However, when this occurs over a lake the waves generated by previous onshore wind subside relatively quickly.

boulder fields

Block fields - large areas covered by blocky boulders created by frost action and mass movement

parabolic dune horns

Crescent-shaped with the steep slip face on the convex side so that the "horns" point upwind. They typically develop where vegetation is available to anchor the horns. In many, the area in front of the dune (between the horns) is a blowout, a small depression excavated by the wind.

Yardang

Desert landform shaped by wind abrasion in the form of narrow linear ridge lying parallel to the prevailing wind direction; most common in dry sandy areas underlain by soft bedrock.(47)

dunes

Dunes are shaped by both deposition and erosion of sediment by the wind, but we classify them as depositional landforms because they develop where, overall, there is more deposition than erosion of windblown sand.

sandspit

Elongated extension of a beach into open water where the shoreline reaches a bay or bend; built and maintained by longshore drift. (49)

Esker

Glacial landform that is a steep-siding, sinuous (winding) ridge; formed by deposition of sand and gravel on the bed of a stream flowing through a tunnel in the glacier ice. When the glacier retreats, the esker is left behind. (44)

Aretes

Knifelike, jagged ridge that separates two adjacent glaciers or glacial valleys. (45)

Deposition of sand dunes: Dune types

Longitudinal Star Barchan (Moon shape) Transverse

Glacial Sediment

Outwash & Glacial drift

deflation hollows

Shallow desert basin created by the wind erosion process of deflation. (47)

Tarn

Small circular lake on the floor of a cirque basin. (45)

truncated spurs

Spurs of hillsides that have been cut off by a glacier thereby straightening the glacially eroded valley. (45)

dunes and vegetation:

The dunes are moving and therefore are not vegatating

Foreshore

The zone that is covered with water during high tide and exposed during lowtime.

wind erosion-

There are two types of wind erosion Deflation = Wind picks up material from one place Abrasion = The thing what wind picked up, hits something else and that starts flowing as well

glacial till -

Till or glacial till is unsorted glacial sediment. 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. (44)

coastal wave and seasons -

Wave action has the effect of straightening a coastline wearing back the promontries and filling in the bays.

calving

____ at the outer edge the ice shelves break into large icebergs. This process is called

pingos-

a mound "believed to form where liquid water moves upward and freezes near the surface. Massive ice builds up and pushes the ground above it into a dome-like shape" ( p. 559) •the core of (blank) is ice, not rock or soil(chapter 46)

Glacier ablation

ablation refers to loss of ice, which occurs largely through melting for most glaciers -zone of ablation is continually resupplied with ice

*

actually only 10% of deserts are covered in sand. and those are usually intermittent dunes that have formed

swash

after the wave loses its form it moves up the shore in a thinning seat, this is the swash

Glacial drift

all of these kinds of sediment put together are glacial drift

frost action

also called frost wedging, form of mechanical weathering, gets in cracks and expands, can't get below permafrost, occurs on the periglacial landscapes

Zone of accumulation

area higher on the glacier where snow is accumulated and turned into ice

Zone of ablation

area of the glacier lower down which is the where ablation (loss of ice) occurs through melting and

recessional moraines

as the ice sheet begins to retreat from its outermost limit, it forms additional moraines where the retreat halts for some time or where there is a minor re-advance of the sheet

Roche moutonne-

complicated process produced by plucking on leeward side.(43)

continental ice sheets

consists of huge masses of ice that is in motion (chapter 43)

patterned ground

created by artesian pressure, in the core there is ice *ice mountain from the ground*

rock flour

debris is ground into the fine particles as the glacier moves down.(44)

Cirques

distinctive amphitheater-like landforms, well developed, are bowl shaped, sleep-sided depressions in the bedrock with a gently sloping floor. (They grow through frost action and headward erosion)(chap 45)

how grains move with the wind

erodes,transports,deposits wind is like a fluid, like water in a river it picks things up and transports things and finally deposits wind happens a lot along the coastline rules of thumb: too big or too small particles are toughest to move, mid size are easiest

Groin

extending into the surf at a 90 - degree angle, mark the beaches of the resort hotels that line the atantic shore of Miami Beach. There structures prevent the excessive loss of sand by beach drift, which piles up on the upcurrent side of each groin. A groyne (groin in the United States) is a rigid hydraulic structure built from an ocean shore (in coastal engineering) or from a bank (in rivers) that interrupts water flow and limits the movement of sediment. ... In the ocean, groynes create beaches or prevent them being washed away by longshore drift.

Ice Shelves

floating extensions of the main antarctic ice sheet or smaller glaciers which remain attached ot the larger ice mass as they protrude from the land into the water

terminal moraines

forms at the outermost limit of the ice sheet during a major advance

Ice Sheet

giant ice dome resting on a landmass

Basal ice

ice near the bottom of the glacier

waves

in the winter waves are bigger and in the summer there is smaller waves -the summer the sand is piled high, by winter its gone because in winter waves are bigger which takes more sand

sandspit

is a deposition bar or beach landform off coasts or lake shores. It develops in places where re-entrance occurs, such as at a cove's headlands, by the process of longshore drift by longshore currents.

kame

is a glacial landform, an irregularly shaped hill or mound composed of sand, gravel and till that accumulates in a depression on a retreating glacier, and is then deposited on the land surface with further melting of the glacier.

Glacial Trough

is the U - shaped landscape (think of yosemite, the bottom part)

pack ice

is the frozen seawater; not the same as icerbergs which are calved (broken) off of glaciers (Ice sheets)

Deglaciation

is the process when it goes from glacial periods to interglacial periods

permafrost table-

it's the uppermost surface! (Does not thaw)

Crevasses

large cracks in upper layer of mountain glaciers. The upper layer is brittle and rigid

hanging valley

much shallower than the larger trunk glacier, the floor of the tributary glacier valley will hang high above the floor of the longer trunk glacier valley *Think of waterfalls in Yosemite* reasons why we have waterfalls

two types of erosional features of glaciers common in mountain glacier landscapes

polished and striated surfaces roches moutonnees

striation

scratches made as the boulder or pebble is dragged along the floor, are called glacial ____ ____ are often meters along the millimeters to centimeters deep they can be useful indicators of the direction of ice movement where the topography provides few other clues

Icecaps

smaller ice areas than ice sheets. These covered much of western US.

Icecaps

smaller ice areas than ice sheets. These covered much of western US.\

baymouth bar-

some sandpits continue to grow all the way across the mouth of a bay.(48)

outwash

sorted materials which are carried off of the glacier by streams of water melting from the glacier

different moraines

terminal moraines and recessional moraines

periglacial-

terrains that are near glaciers or the perimeter of glaciation.

ice-wedge polygons

the above mentioned freeze thaw wedging creates a network of cracks which form ice wedges polygons; cracks can be filled with sand; results from ice wedges are cracks in landscapes

Interglacial period

the climate continues to warm during the interglacial period between glacial periods

Tides-

the cyclical rise and fall of sea level along ocean coasts as a result of moons gravitational pull. Sea level rises and falls twice each day.(48)

fetch

the distance traveled by wind or waves across open water.

Frost heaving

upward pushing of underground rock fragments and soil when ice forms under them and expands

frost heaving

upward pushing of underground rock fragments and soil when ice forms under them and expands...(chapter 46)

Glacial periods

when Earth's atmosphere became much cooler than it is at present. Great expansion of ice sheets in high to middle latitudes and growth of large glaciers in mountains where they are small or nonexistent today.

tombolo sea stack-

when a sandspit forms a link between an offshore island and the mainland (48)

backwash

when the water goes back

littoral zone

where coastal processes happen, also where the land meets the sea

glacial surge-

•Glaciers move slowly. Occasional "_____" move the placer 1/meter per hour -movement of the entire glacier over the rocks below it. Not all glaciers move by slid ing but this is responsible for the erosion done be glaciers