Page 273 - Fundamentals of Geomorphology

Table 10.2 Landforms created by glacial erosion
Landform Description

Abrasion by glacier ice – streamlined relief forms (mm to 1000s km)
Areal scouring Regional expanses of lowland bedrock, up to 1000s km in extent, scoured by ice.
Sometimes contain sets of parallel grooves and bedrock flutes
Glaciated valley Glacial trough, the floor of which is above sea level. Often U-shaped
Fjord Glacial trough, the floor of which is below sea level. Often U-shaped
Hanging valley Tributary valley whose floor sits above the floor of the trunk valley
Breached watershed Col abraded by a valley glacier spilling out of its confining trough
Dome Dome-shaped structure found in uniform bedrock where ice has abraded an obstacle to
leave a smoothed rock hillock that has been subject to exfoliation after the ice has left
Whaleback or rock drumlin Glacially streamlined erosional feature 100–1000 m long, intermediate in size between a
roche moutonnée and a flyggberg
Striation Scratch on bedrock or clast made by ice (or other geomorphic agents such as landslides,
tectonic disturbance, and animals)
Polished surface Bedrock surface made shiny by a host of tiny scratches scored by fine-grained clasts
Groove A furrow cut into bedrock by fragments of rock (clasts) held in advancing ice
Plastically moulded forms Smooth and complex forms on rock surfaces. They include cavetto forms (channels on
(p-forms) steep rock faces) and grooves (on open flat surfaces). Sichelwannen and Nye channels
(curved and winding channels) are also p-forms, but probably produced mainly by
meltwater erosion (Table 10.3)

Abrasion and rock fracturing by glacier ice – partly streamlined relief forms (1 m to 10 km)
Trough head Steep, rocky face at the head of many glaciated valleys and fjords
Rock or valley step Bedrock steps in the floor of glacial troughs, possibly where the bedrock is harder and
often where the valley narrows
Riegel Low rock ridge, step, or barrier lying across a glaciated-valley floor
Cirque Steep-walled, semi-circular recess or basin in a mountain
Col Low pass connecting two cirques facing in opposite directions
Roche mountonnée Bedrock feature, generally less than 100 m long, the long axis of which lies parallel to the
direction of ice movement. The up-ice (stoss) side is abraded, polished, and gently
sloping, and the down-ice (lee) side is rugged and steep
Flyggberg Large (>1000 m long) streamlined bedrock feature, formed through erosion by flowing
ice. The up-ice (stoss) side is polished and gently sloping, whereas the down-ice (lee)
side is rough, irregular, and steep. A flyggberg is a large-scale roche moutonnée or
whaleback. The name is Swedish
Crag-and-tail or lee-side cone An asymmetrical landform comprising a rugged crag with a smooth tail in its lee
Rock crushing – non-streamlined relief forms (cm to 10s cm)
Lunate fracture Crescent-shaped fractures with the concavity facing the direction of ice flow
Crescentic gouge Crescent-shaped features with the concavity facing away from the direction of
ice flow
Crescentic fracture Small, crescent-shaped fractures with the concavity facing away from the direction of
ice flow
Chattermarks Crescent-shaped friction cracks on bedrock, produced by the juddering motion of
moving ice

Erosion by glacier ice, frost shattering, mass movement – residual relief forms (100 m to 100 km)
Arête Narrow, sharp-edged ridge separating two cirques
Horn Peak formed by the intersecting walls of three or more cirques. An example is the
Matterhorn
Nunatak Unglaciated ‘island’ of bedrock, formerly or currently surrounded by ice
Source: Adapted from Hambrey (1994, 84)