Grade 9 Geography – Unit 3
Glaciation Definitions
Term
Definition
Arête
A thin, almost knife-like, ridge of rock which is typically formed when
two glaciers erode parallel U-shaped valleys. The arête is the thin
ridge of rocks remaining after glaciation.
Alpine Glacier
Glacier occupying one or more valleys in an alpine region. Glacier
movement is downward from high elevations to low elevations under
the force of gravity
Cirque
An amphitheatre-like valley, or valley head, formed by erosion at the
head of a glacier. To make this formation, the glacier has a rotational
slide that abrades the floor of the basin BUT not the edges. This
process causes a bowl shape to form.
Continental Glacier
Glacier that spread out to cover a large area. Glacier movement is by
their own weight.
Drumlin
Geologic feature formed by ice sheets. An “egg-shaped” hill with a
steep side at the wide end and a gentle slope on the other side
Erratic
Rock picked up by ice, carried along and deposited many kilometres
away. It is easily identifiable because the rock composition is different
from the bedrock in the region in which the rock was deposited. An
erratic change range in size from pebbles to large boulders. Esker
A long ridge of material deposited by a melt water stream flowing from
beneath a glacier. Esker are like railroad embankments Horned Peak
When a cirque erodes leaving only a sharp peak flanked by nearly
vertical headwall cliffs. The most famous horned peak is the
Matterhorn in Switzerland.
Lake Plain
Fertile bottom of an ancient glacier lake. Now, the land is typically
highly sought for agriculture.
Moraine
Unconsolidated debris or material deposited by a glacier, often in the
form of hills. For example, a terminal moraine is formed at the
farthest point reached by a glacier.
Spillway
A deep valley created by large volumes of water flowing from a
melting Continental Glacier. Once the ice sheet melted, the spillway
became the path for a small stream called MISFIT STREAM.
Striation
In glaciation, a groove often gouged out in the bedrock under the ice
sheet by rocks frozen in the ice. Till Plain
Flat to gentle hilly area created by glacial deposition.