Glacial Landforms 1 Flashcards
(19 cards)
What is a Cirque?
An armchair-shaped hollow on a hillside above a glacial valley.
Also known as corries or cwms.
Define Arete.
A narrow ridge between two cirques.
Formed as two cirques erode back to back.
What is a Pyramidal peak?
A sharp, pointed hilltop.
Created by the erosion of three or more cirques.
Describe a Glacial trough.
A steep-sided, flat-floored straight valley.
Formed by the widening and deepening of a pre-glacial river valley.
What is a Truncated spur?
A steep and possibly rocky section of the side of a trough.
Result of erosion from a powerful glacier.
Define a Hanging valley.
A small tributary valley high above the floor of the trough, often with a waterfall.
Formed by tributary glaciers that did not erode as deeply.
What is a Ribbon lake?
A long narrow lake along the floor of a glacial trough.
Sometimes formed behind a terminal moraine after glaciation.
Describe Roche moutonnees.
Asymmetrical, bare rock outcrop with a gently sloping side facing up-valley.
Formed due to the scouring effects of a glacier.
What are Knock and Lochan?
A lowland area with alternating small rock hills (knock) and hollows, often containing small lakes (lochan).
Result of glacial scouring.
Define Crag and tail.
A very large mass of hard rock forms a steep stoss with a gently sloping tail of deposited material.
Created by differential erosion during glacial movement.
How is a Cirque formed?
A pre-glacial hollow is enlarged by plucking and abrasion as ice moves in a rotational manner under gravity.
What process leads to the formation of an Arete?
As two cirques are enlarged back to back, the ridge between them becomes increasingly narrowed.
How does a Pyramidal peak develop?
As three or more cirques are enlarged, the hilltop between them becomes increasingly sharp and pointed.
What causes a Glacial trough?
A pre-glacial river valley is widened and deepened by erosion from an advancing glacier.
How does a Truncated spur form?
The pre-glacial interlocking spurs of the river valley are eroded by the glacier.
What is the formation process of a Hanging valley?
Tributary glaciers with small amounts of ice do not erode their valley floor as deeply as the main glacier.
Describe how a Ribbon lake is formed.
Areas of increased plucking and abrasion by the valley glacier deepen part of the valley floor.
What happens to the up-valley side of a Roche moutonnee?
It is smoothed by abrasion due to increased pressure from the glacier.
What is the effect of glacier velocity on the formation of a Crag and tail?
Reduced glacier velocity on the lee protects softer rock and allows deposition.
