Monday
March 21, 2011
(Landforms Created
by Glacial Erosion;
Glacial Deposits)
The Launch Pad
Monday, 3/21/11
Why are most glaciers
in the world today
receding?
The Launch Pad
Monday, 3/21/11
More ice is melting every
summer than can be replaced by
snowfall the next winter. This
could be caused by a gradual
increase in world temperatures
(global warming.)
Announcements
??
Assignments For This Six-Weeks
Date Issued
Date Due
Video Quiz - Lakes, Rivers, and Other
Water Sources
2/27
2/27
WS - Running Water and Groundwater
(Part 1)
2/25
3/4
PowerPoint Project – Rivers (P5
only)
2/28
3/3
WS - Running Water and Groundwater
(Part 2)
3/2
3/9
Video Quiz - Groundwater
3/3
3/3
Cornell Notes - Ice
3/8
3/9
WS - Ice
3/9
??
Ice
Landforms Created by Glacial Erosion
Certain types of special landforms can be
created by glacial erosion. These include:
glacial troughs – As a glacier widens, deepens,
and straightens a valley, it transforms a vshaped valley into a u-shaped glacial trough.
hanging valleys – After a glacier has receded,
the valleys of tributary glaciers are left standing
above the main glacial trough and are termed
hanging valleys.
Landforms Created by Glacial Erosion
cirques – a bowl-shaped depression at the
head of a glacier that was a depression
where snow could accumulate, thus
starting the formation of the glacier.
arêtes – sharp-edged ridges that are
formed when cirques grow and the divide
separating them becomes very narrow.
Landforms Created by Glacial Erosion
horns – several cirques surrounding a
single mountain create the spires of rock
called horns.
fiords - glacial troughs that became
submerged as the ice left the valley and
sea levels rose following the Ice Age
Erosional Landforms Created by Alpine Glaciers
Figure 6.10 C
The Matterhorn in the Swiss Alps
Figure 6.12
Figure 6.10 (top right)
Figure 6.10 (middle right)
Figure 6.10 (bottom right)
Figure 6.11A
Figure 6.11B
Glacial Deposits
Glaciers pick up and transport a huge load of debris as they slowly
advance across the land.
Ultimately, these materials are deposited when the ice melts.
In regions where glacial sediment is deposited, it can play a significant
role in forming the physical landscape.
Long before the theory of an extensive Ice Age was proposed, much of
the soil and rock debris covering portions of Europe was recognized as
coming from elsewhere.
At the time, these foreign materials were believed to have been
“drifted” into their present positions by floating ice during an ancient
flood.
Therefore, the term drift was applied to this sediment.
Today, glacial drift is a term for sediments of glacial origin, no matter
how, where, or in what form they were deposited.
Glacial Deposits
Types of Glacial Drift
Till refers to material that is deposited directly by ice.
Glacial Deposits
Types of Glacial Drift
Stratified drift is a sorted sediment deposited by meltwater.
Glacial Deposits
Types of Glacial Drift
Boulders found in till or lying
free on the surface are called
glacial erratics if they are
different from the bedrock
below.
Erratics must have been
derived from a source outside
the area where they are
found.