Test 4

eskers

A meandering, water-deposited, generally steep-sided sediment ridge that forms within a subglacial stream channel

horn

A pointed, mountain peak, typically pyramidal in shape, bounded by the walls of three or more cirques.

erratics

A rock of unspecified shape and size, transported a significant distance from its origin by a glacier or iceberg and deposited by melting of the ice.

U-Shaped Valley

Alpine glaciers completely fill their valley to depths of hundreds of feet. This creates wide-bottomed and very steep-sided valleys due to the erosion and scouring of both the floor and the valley walls.

Parabolic Dunes

Also known as "blowouts"; the crest is curved with the tails pointing against the wind direction

drumlins

An elongated ridge of glacial sediment sculpted by ice moving over the bed of a glacier. The shape is often compared to an inverted, blunt-ended canoe. Generally, the down-glacier end is oval or rounded and the up-glacier end tapers.

roches moutonnees

An elongated, rounded, asymmetrical, bedrock knob produced by glacier erosion. It has a gentle slope on its up-glacier side and a steep- to vertical-face on the down-glacier side. Sometimes called rock drumlins.

ice caps

An ice cap is a large mass of ice that originates on land by compaction and recrystallization of snow. Ice caps flow outwards in several directions and cover most or all features of underlying land.

ice front

An ice front is the place where a glacier thins and ends. The ice front's position changes as the glacier moves or melts

ice sheet

An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km².

till

An unsorted and unstratified accumulation of glacial sediment, deposited directly by glacier ice.

Gyres

These are circular wind-driven currents that exist in every ocean.

Inselbergs

These are outcrops of bedrock that are partly buried by sediment (usually on a bajada)

Alluvial fans

These are water-carried deposits formed at the mouth of desert canyons. They look a lot like deltas—the only difference is that there is no water body to deposit the sediment in.

Barchan Dunes

These dunes have a curved crest like parabolic dunes but the tails point with the wind

Longitudinal Dunes

These dunes have crests that are parallel to the wind; These are spaced hundreds of meters apart

Yardangs

These features are scoured by wind erosion and streamlined parallel to the wind. Yardangs are not dunes—they are erosoional remnants not deposits.

Bajada

This is a gently sloping apron of sediment at the base of a mountain range formed when alluvial fans merge together.

Cross bedding

This is what the layers inside a dune look like. The beds dip along the angle of the slip face. Overall, the larger scale bedding is still horizontal.

Star Dunes

This type of dune forms if there are multiple dominant wind directions

Medial moraine

Two lateral moraines that merge where two glaciers intersect

Longshore drift

Waves that approach the shoreline from an angle create a current that flows along the shore, moving sediment down the beach.

Inundation

What process occurs on a barrier island during storms that causes barrier islands to migrate landward, depositing the lobes of sand you see on the sound side?

Desert varnish

When exposed surfaces are wetted, a thin layer of mineral varnish (manganese) precipitates on the rock. Algae can also be found in rock varnish.

Desert Pavement

Wind winnows away fine sediment such as silt and sand but leaves larger gravel and rocks on the surface.

Transverse dunes

e crest of this type of dune is perpendicular to the wind direction

Tombolo

spit-like extensions that connect nearshore islands to the mainland shore.

Natural Arch/Bridge

. Arches have a hard cap rock and weak rock that erodes from underneath.

Horn

: A sharp peak created by glacial erosion on all sides

Playa

: An ephemeral desert lake bed.

Slip Face

: Sand accumulates at the crest of a dune until its slope exceeds the angle of repose. It collapses or slides down the leeward slope.

Evaporite (salt)

: When desert lakes evaporate, minerals that were dissolved in the water precipitate as salt crystals. There are dozens of different evaporate minerals. Salt crystals can build up into beautiful formations like this.

Fjord

A U-shaped valley that is an inlet to the sea. These channels can be hundreds of feet deep

cirque

A bowl-shaped, amphitheater-like depression eroded into the head or the side of a glacier valley. Typically, a cirque has a lip at its lower end. The term is French and is derived from the Latin word circus.

outwash plains

A broad, low-slope angle alluvial plain composed of outwash that has been transported by meltwater. The alluvial plain begins at the foot of a glacier and may extend for miles.

Paternoster Lakes

A chain of lakes found in a formerly glaciated valley; each is impounded and separated from the others by moraine deposits

kettles

A depression that forms in an outwash plain by the melting of a block of glacier ice that was separated from the retreating glacier and was subsequently buried by glacier sedimentation. As the buried ice melts, the depression enlarges

Mesa

A flat-topped mountain. The top of a mesa is usually a hard layer of rock, and the base is made of softer rock

arête

A jagged, narrow ridge that separates two adjacent glacier valleys or cirques. The ridge frequently resembles the blade of a serrated knife. A French term referring to the bones in a fish backbone.

valley glacier

Commonly originating from mountain glaciers or ice fields, these glaciers spill down valleys, looking much like giant tongues.

outwash

Glacially eroded, sorted sediment that has been transported by meltwater. Typically, the sediment becomes finer grained with increasing distance from the glacier terminus.

striations

Multiple, generally parallel, linear grooves, carved by rocks frozen in the bed of a glacier into the bedrock over which it flows.

Lateral Moraine

Sediment ridge deposited along the sides of a glacier

Butte

Similar to a mesa but smaller and narrower in size

Hanging Valley

Small valley that intersect a deeper U-shaped valley. The floor of the larger valley is often hundreds of feet below the smaller valley—making waterfalls common!

glacial trough

Steep-sided, flat-bottomed valley formed by a glacier. A U-shaped valley.