18 wind erosion

Geology 12
Presents




Outline:
• Chp 14
• Chp 15
• Chp 16
• Chp 17
• Chp 18

Mass Wasting (Landslides)
Running Water
Groundwater
Glaciers and Glaciation
Wind and Deserts


Glaciers and
Glaciation
A: Introduction
B: Glacial Erosion and Transport
C: Glacial Deposits


Glaciers


A: Introduction/Glaciers

•

Glacier: mass of ice composed of
compacted snow and recrystallized snow
flowing under its own weight under the
force of gravity.
• Move via:
1. plastic deformation below 40m just from the
shear weight of ice.
2. basal slip: sometimes with the presence of
melt water the glacier may slide.


Glacier Movement


Glacier Movement


•Copy diagram
Crevasse
Total surface movement
40m

Plastic deformation

Basal slip

Types of Glaciers
1. Valley/Alpine Glaciers: confined to mountain
valleys (yoodle leh)
• Flow down hill
• Few km wide by 10’s of km long by several
100 m thick
• Ex: Alaskan Alpine Glaciers
2 km wide x 120 km long x 400 m thick

ice


1. Valley/Alpine Glaciers


Types of Glaciers
2. Ice Sheets: BIG
• Flow out horizontally in every direction from
where the snow accumulates the most
a) Continental Glaciers:
• Largest: 100s of km long/wide by 3-5 km
thick
• Ex: Greenland, Antarctica (now) and N.
Amer’ during the last ice age 25,000 yrs
ago (most of Canada)


Ice Sheets: Continental Glaciers

Types of Glaciers
2. Ice Sheets:
b) Ice Caps
• <50,000 km2
• Ex: Penny Ice Cap (Baffin Isld), Iceland,
Spitsberg Isld.
ice
crust

isostacy


Ice Sheets: Ice Caps


Isostasy


• Glacial Movement
Zone of accumulation
Firn limit
snow
ice

Zone of
wastage
Ice front

Firn: pebbles of ice; intermediate stage
between snow and ice

Glacial Movement
Firn: Pebbles of ice
•Intermediate stage between
snow and ice


Firn


Glacial Movement
Glacial advance: when accumulation > wastage
Glacial Retreat: when accumulation < wastage


Glacial Movement
Glacial advance: when accumulation > wastage
Glacial Retreat: when accumulation < wastage



• Calving: process of
producing icebergs.

gla
ci

er

ocean


• Calving: process of
producing icebergs.


Icebergs