Chapter 2 Glaciated landscapes

Flashcards about Glaciated Landscapes

Glacio-fluvial landforms

Landforms produced by meltwater from glaciers, including both erosional and depositional features.

Outwash

Distinctive sediment type deposited by glacio-fluvial streams and rivers, characterized by generally smaller, smooth, rounded, sorted, and stratified particles in contrast to till.

Jökulhaups

Extreme glacial outbursts caused by geothermal or volcanic activity beneath glaciers, leading to massive and sudden melting.

Kame

A hill or hummock composed of stratified sand and gravel laid down by glacial meltwater, with two types: delta kames and others formed by en-glacial streams or debris-filled crevasses.

Delta kames

Formed by en-glacial streams emerging at the snout of the glacier, supraglacial streams depositing material on entering ice-marginal lakes, or debris-filled crevasses collapsing during ice retreat.

Esker

A long, sinuous ridge composed of stratified sand and gravel laid down by glacial meltwater in sub-glacial tunnels as the supply of meltwater decreases at the end of the glacial period.

Ice-contact drift

Material deposited under or against the ice, tending to be more sub-rounded and less well sorted than outwash material.

Kame terraces

Ridges of material running along the edge of the valley floor, formed by supraglacial streams depositing lateral moraine as the glacier retreats.

Erratic

An individual piece of rock composed of a different geology from that of the area in which they have been deposited.

Drumlin

A mound of glacial debris that has been streamlined into an elongated hill, typically pear-shaped and aligned in the direction of ice flow.

Till sheet

A large mass of unstratified drift deposited at the end of a period of ice sheet advance, smoothing the underlying surface and variable in composition based on the rocks over which the ice has moved.

Lichenometry

A method of numerical dating that uses the size of lichen colonies on a rock surface to determine the surface's age.

Terminal moraine

A ridge of till extending across a glacial trough, marking the position of the maximum advance of the ice, usually steeper on the up-valley side.

Lateral moraine

A ridge of till running along the edge of a glacial valley, accumulating from material weathered from the exposed valley sides on top of the glacier.

Recessional moraines

A series of ridges running transversely across glacial troughs, broadly parallel to each other and to the terminal moraine, found further up the valley and formed during temporary still-stands in retreat.

Roche moutonnées

Projections of resistant rock on the floor of glacial troughs, smoothed and striated on the up-valley side by abrasion and steepened on the down-valley side by plucking.

Ellipsoidal basins

Major erosional landforms created by ice sheets, such as those formed by the Laurentide ice sheet in North America.

Troughs

Glaciers flow down pre-existing river valleys under gravity, causing the shape to become deeper, wider and straighter.

Corries

Armchair-shaped hollows found on upland hills or mountainsides with a steep back wall, an over-deepened basin, and often a lip at the front.

Arête

A narrow, steep-sided ridge found between two corries, forming from glacial erosion and the retreat of corries that are back to back or alongside each other.

Pyramidal peak

A steepened mass formed where three or more corries develop around a hill or mountain top and their back walls retreat.

Glacio-fluvial landforms Formation

1. Glacial meltwater erodes and deposits sediments.
2. Streams sort and transport material, creating diverse landforms.
3. Features include valleys, plains, and terraces shaped by water flow.

Outwash Formation

1. Glacial meltwater streams carry sediments away from the glacier.
2. Sediment is sorted, rounded, and stratified during transport.
3. Deposits form expansive outwash plains with smaller, smoother particles.

Jökulhaups Formation

1. Geothermal or volcanic activity melts ice beneath a glacier.
2. Meltwater accumulates until it breaches the ice dam.
3. A sudden, massive flood occurs, reshaping the landscape.

Kame Formation

1. Meltwater deposits sediment in various locations on or near the glacier.
2. Delta kames form at the snout, supraglacial streams deposit material, or crevasses collapse.
3. Accumulation of stratified sand and gravel results in a hummock or hill.

Delta kames Formation

1. En-glacial streams emerge at the glacier's snout.
2. Supraglacial streams deposit material into ice-marginal lakes.
3. Debris-filled crevasses collapse during ice retreat, forming stratified deposits.

Esker Formation

1. Meltwater flows through sub-glacial tunnels.
2. Sediment is deposited within the tunnels as water flow decreases.
3. As the glacier retreats, the sediment remains as a long, sinuous ridge.

Ice-contact drift Formation

1. Material is deposited directly under or against the ice.
2. Sediments are typically sub-rounded and less well sorted than outwash.
3. Landforms retain characteristics influenced by direct contact with the ice.

Kame terraces Formation

1. Supraglacial streams deposit lateral moraine along the valley edge.
2. Glacier retreats, leaving ridges of material along the valley floor.
3. Terraces run along the valley, marking the former glacier's edge.

Erratic Formation

1. Rock is transported by glacial ice over long distances.
2. Glacier deposits the rock in an area with different geology.
3. The rock stands out as foreign material in its new location.

Drumlin Formation

1. Glacial debris accumulates beneath the ice.
2. Ice flow streamlines and elongates the debris into a hill.
3. The streamlined shape aligns with the direction of ice flow.

Till sheet Formation

1. Ice sheet advances and deposits unstratified drift.
2. Drift smooths the underlying surface.
3. Forms a large mass of variable composition based on the rocks over which the ice has moved

Lichenometry Formation

1. Lichen colonies grow on a rock surface after it is exposed.
   2. The size of the lichen is measured.
2. The surface's age is determined based on the growth rate of the lichen.

Terminal moraine Formation

1. Till accumulates at the glacier's maximum advance.
2. Ridge of till extends across a glacial trough.
3. Marks the furthest extent of the ice, often steeper on the up-valley side.

Lateral moraine Formation

1. Material weathers from valley sides onto the glacier.
2. Till accumulates along the edge of the glacial valley.
3. Forms a ridge running along the valley, parallel to the glacier's edge.

Recessional moraines Formation

1. Glacier retreats with temporary still-stands.
2. Ridges form transversely across glacial troughs during these pauses.
3. Parallel to each other and the terminal moraine, but further up the valley.

Roche moutonnées Formation

1. Projections of resistant rock exist on the glacial trough floor.
2. Abrasion smooths and striates the up-valley side.
3. Plucking steepens the down-valley side.

Ellipsoidal basins Formation

1. Ice sheets erode the landscape over extensive periods.
2. Major erosional landforms are created.
3. Large basins formed by significant ice sheet activity

Troughs Formation

1. Glaciers flow down pre-existing river valleys.
2. Glacial action deepens, widens, and straightens the valley.
3. Creates a characteristic U-shaped valley.

Corries Formation

1. Snow accumulates in a hollow on a hillside.
2. Freeze-thaw action and glacial erosion deepen and widen the hollow.
3. Forms an armchair-shaped feature with a steep back wall and over-deepened basin.

Arête Formation

1. Two corries form back-to-back or alongside each other.
2. Glacial erosion causes the corries to retreat.
3. A narrow, steep-sided ridge is left between the corries.

Pyramidal peak Formation

1. Three or more corries develop around a hill or mountain top.
2. The back walls of the corries retreat.
3. A steepened mass is formed, creating a pyramidal peak.