Glaciers, Deserts and Wind
Types of Glaciers
A _________________ is a thick ice mass that forms above the
________________ over hundreds or thousands of years.
The ______ ________ was a period of time when much of the Earth was
covered in glaciers.
Valley Glaciers
Ice masses that slowly _______________ down mountain valleys originally
occupied by streams.
A stream of ice that flows between steep rock walls from near the top of the
mountain valley.
Ice Sheets / Continental Glaciers
_____________________ are enormous ice masses that flow in all directions
from one or more centers and cover everything but the highest land.
Ice sheets are sometimes called ______________ ice sheets because they
cover large regions where the climate is extremely ________.
They are ________ compared to valley glaciers
They currently cover __________________ and ____________________.
How Glaciers Move
The movement of glaciers is referred to as _______, and it happens in two ways.
1. Plastic flow— _____________________________________________
2. Basal slip— _______________________________________________
Budget of a Glacier
The glacial budget is the ______________, or lack of balance, between
__________________ at the upper end of a glacier and loss, or ____________,
at the lower end.
Glacial Erosion
Many landscapes were changed by the widespread glaciers of the recent ice
age.
How Glaciers Erode
● Plucking— ______________________
● ____________
- Rock flour (pulverized rock)
- __________________ (grooves in the bedrock)
Landforms Created by Glacial Erosion
Glaciers are responsible for a variety of _____________ landscape features,
such as glacial troughs, ______________ valleys, __________, arêtes, and
__________.
Glaciated Valleys
A _______________________ is a U-shaped valley that was once
________________ but was deepen by a glacier.
A ____________ is a bowl-shaped depression at the head of a glacial valley.
Arêtes and Horns
•
Snaking, ________-edged ridges called ___________ and sharp pyramidlike peaks called ________ project above mountain landscapes.
Glacial Deposits
Types of Glacial Drift
Glacial drift applies to all sediments of glacial origin, no matter how, where, or in
what form they were deposited.
There are two types of glacial drift.
1. ________ is material deposited directly by the glacier.
2. ______________________ is sediment laid down by glacial meltwater.
Moraines, Outwash Plains, and Kettles
Glaciers are responsible for a variety of depositional features, including
_____________________—layers or ridges of till
- Lateral
- Medial
- Terminal end
Glaciers are responsible for a variety of depositional features, including
___________________—sloping plains consisting of deposits from meltwater
streams in front of the margin of an ice sheet
________________—depressions created when a block of
ice becomes lodged in glacial deposits and subsequently melts
______________ —streamlined, asymmetrical hills composed of glacial dirt
__________—ridges composed largely of sand and gravel deposited by a
stream flowing beneath a glacier near its terminus
Glaciers of the Ice age
Ice Age
Began ____ to ____ million years ago
Division of geological time is called the ________________ epoch
Ice covered _____% of Earth's land area.
Greatly affected _________________
Many ice ages since from this time, including the last one approx.
_______________ years ago. (Wisconsin Ice Sheet)
Geologic Processes in Arid Climates
Weathering
Much of the weathered ____________ in deserts results from mechanical
weathering.
Chemical weathering is not completely _____________ in deserts. Over long
time spans, clay and ______ soils do form.
• Not as effective as in ___________ regions
The Role of Water
In the desert, most streams are _________________—they only carry water
after it rains.
Deserts
Basin and Range: A Desert Landscape
Most desert ______________ dry up long before they ever reach the
____________. The streams are quickly depleted by ________________ and
soil infiltration.
Interior drainage into basins produces
_______________________—a fan-shaped deposit of sediment formed when a
stream’s slope is abruptly reduced
______________________—a flat area on the floor of an undrained desert basin
(playa) that fills and becomes a lake after heavy rain
Most desert erosion results from _____________water. Although wind erosion is
more ________________ in deserts than elsewhere, ____________ does most
of the erosional work in deserts.
Wind Erosion
Wind erodes in the desert in two ways
1. _________________ is the lifting and removal of loose particles such as clay
and silt. It produces
blowouts
_______________________—a layer of coarse pebbles and gravel created
when wind removed the finer material
Wind Deposits
The wind can create _________________ when it deposits its sediments,
especially in deserts and along ___________. Both layers of ________ and sand
dunes are landscape features deposited by the ________.
Loess
Deposits of ________________ silt
Extensive ______________deposits
Primary sources are ______________ and glacial stratified drift.
Sand Dunes
Unlike deposits of loess, which form blanket-like layers over broad areas, winds
commonly deposit sand in mounds or ridges called ___________.
• Characteristic features
- Slip face is the _____________slope of the dune
- _____________________ are the sloping layers of sand in the dune.
Types of Sand Dunes
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1.
2.
3.
4.
5.
6.
What form sand dunes assume depends on the wind direction and speed,
how much sand is available, and the amount of vegetation.