Geoscience Reference
In-Depth Information
C H E C K Y O u R u N D E R S T A N D I N G
1.
Why are summertime temperatures a critical variable
with respect to the formation of a glacier?
8.
In what two regions of Earth are large continental
glaciers currently found?
2.
Describe the steps involved in the metamorphosis of
snow to glacier ice.
9.
What is the difference between glacial till and glacial
outwash? What are the diagnostic characteristics of
each deposit?
3.
How does a glacier flow? Where does the ice move the
fastest and slowest? Why?
10.
How does the formation of a recessional moraine differ
from that of a terminal moraine?
4.
Compare and contrast the various kinds of glaciers on
Earth.
11.
Explain the history of glaciations on Earth.
5.
Describe the difference between glacial abrasion and
glacial plucking. What landform is produced by a combi-
nation of these two processes?
12.
What is the impact of ongoing climate change on most
glaciers around the world?
13.
What is the difference between continuous and
discontinuous permafrost? What is their geographical
distribution, and why does it make sense given your
understanding of permafrost processes?
6.
How can you tell if a mountainous landscape has
been glaciated? What are some of the characteristic
landforms that should be present if the landscape was
glaciated?
14.
What is ground ice? Describe two landforms created
by this phenomenon.
7.
How does a hanging valley form?
ANSWERS TO VISUAL CONCEPT CHECKS
V I S U A L C O N C E P T C H E C K 1 7 . 1
The glacial mass budget refers to the balance between snow accumulation in the source area and
melting in the zone of ablation. The point where these two processes are in balance is known as the
equilibrium line. Below the equilibrium line, crevasses are visible, whereas above the equilibrium line
they are covered with snow.
V I S U A L C O N C E P T C H E C K 1 7 . 2
Glaciers modify alpine landscapes in a very intense way. Prior to glaciation, alpine landscapes are
generally rounded, with streams flowing in V-shaped valleys. Through the combined processes of
abrasion and plucking, alpine glaciers cause mountainous regions to become more angular, forming
features such as cirques, arêtes, and horns. Valley glaciers enlarge and deepen former stream valleys,
changing them to U-shaped valleys.
V I S U A L C O N C E P T C H E C K 1 7 . 3
This photograph of a stream system in the Southern Alps of New Zealand is a nice example of how
outwash plains form. Several lines of evidence point to this conclusion. The snow-capped peaks in
the background suggest that alpine glaciers are present, which must be delivering coarse sediment to
the stream in glacial meltwater. You can tell that the sediment is coarse because the stream is braided.
Given that fluvial deposition is occurring, you can surmise that the landscape will have very limited
relief and will thus be consistent with an outwash plain.
