Transcript Chapter 8, section 4: Glaciers - Welcome to Mr. Sturken`s Earth

Glaciers
Prentice Hall Chapter 8,
Section 4
By Rusty Sturken
December, 2006 - 2009
Duluth Middle School
Sixth Grade Earth Science
1
Glaciers

A glacier is any large mass of ice that moves
slowly over land.
*Glaciers only form in areas where more
snow falls than melts
*Snow builds up year after year
*Pressure on the snow at the
bottom turns it into ice
*Gravity pulls the glacier
downhill
2
Glaciers
•
•
A valley glacier is a long, narrow glacier that
forms high in a mountain valley
*
flows a few centimeters to a few meters per day
A continental glacier is a glacier that covers
much of a continent or large island
*much larger than valley glaciers
*spreads out like pancake batter
* cover Antarctica and Greenland
3
Glaciers
Valley glacier
pubs.usgs.gov/of/2004/1216/images/mendenhall.gif
Continental glacier
www.uwsp.edu/.../glacier_Ellesmere_GSC.jpg
4
Continental Glaciers



Continental glaciers cover about 10% of Earth’s
surface
The glacier covering Antarctica is over 14
million square kilometers and 2 kilometers thick
An Ice Age is a time when continental glaciers
cover large parts of Earth’s surface
* The last ice age ended 10,000 years
ago.
* Ice has covered 1/3 of Earth
5
Glacial Erosion



The two processes by which glaciers erode
the land are plucking and abrasion
Plucking is the process when glaciers pick up
rocks as they flow over the land, the rock freezes
to the bottom of the glacier
Abrasion is the grinding away of rock by other
rock particles carried in water, ice, or wind.
Rocks frozen to the bottom of a glacier scrape
across rocks on the Earth’s surface.
6
Glacial Deposition




When a glacier melts, it deposits the
sediment it eroded from the land, creating
various landforms.
Till is the mixture of sediments that a glacier
deposits directly on the surface of the Earth.
A moraine is a ridge of till deposited at the
edge of a glacier.
A terminal moraine is the ridge of till at the
farthest point reached by a glacier.
7
www.uwsp.edu/.../images/titles/moraines.gif
Great website
8
Moraines
Terminal moraines and end moraines are the
same thing
www.uwsp.edu/.../images/titles/moraines.gif
9
http://www.belmont.sd62.bc.ca/teacher/geology12/photos/glaciers/lateral_moraine2.jpg
Long Island, N.Y. is a terminal moraine from
the last ice age
http://www.coolantarctica.com/Shop/cities/Long_island_small.jpg
http://image.weather.com/imageat/regions/northeast_sat_720x486.jpg
10
Glaciers
http://www.wildnatureimages.com/S%20to%20Z/SALMON-GLACIER-CAMPER..jpg
http://pubs.usgs.gov/of/2004/1216/glaciertypes/images/glacierpolar1.gif
http://upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Tschierva_glacier_1.jpg/600px-Tschierva_glacier_1.jpg
11
Formations from glaciers








Moraines
Cirques(bowls)
Arêtes
Horns
Fiords
U-shaped valleys
Glacial lakes
Kettle lakes
Background photo from:
Teton Glacier in Grand Teton National Park, Wyoming
12
www.swisseduc.ch/.../icons/cirque-glacier.jpg
See Page 272
Prentice Hall Science Explorer, Earth Science
2002, 2001 Pearson Education, Inc.
13
See Page 273
Prentice Hall Science Explorer, Earth Science
2002, 2001 Pearson Education, Inc.
14
Cirque

A bowl-shaped hollow eroded by a glacier
www.geocities.com/gibell.geo/cirque/overview.html
Logan Mountains, Northwest Territories, Canada
15
Arête

A sharp ridge separating two cirques (bowlshaped hollows)
z.about.com/d/geology/1/0/K/K/arete.jpg
16
Horn

Sharpened peak formed when glaciers carve
away the sides of a mountain.
http://www.homepage.montana.edu/~geol445/hyperglac/eroland1/horn2.JPG
Glacier N.P.
17
Fiord

Form when sea level rises, filling a glacier-cut
valley
http://www.southlandnz.com/sections/move/fiord/
18
Kettle

Forms when depression in till fills with water
www.sfu.ca/~jkoch/older_stuff/glacier%20glossary%20photos/fiord.JPG
19
Fiord/ U-shaped valley
http://www.arcticnet.org/00037245-007EA71E.4/pang%20fiord.jpg
20
Glacial Lakes

Form in long basins created by plucking and
abrasion
Great Lakes
www.ssec.wisc.edu/~gumley/modis_gallery/image.
Excellent website
Finger Lakes in New York
http://earthobservatory.nasa.gov/Newsroom/NewImages/Images/Fin
gerLakes_ISS010E09366_lrg.jpg Also excellent website
21
THANK YOU to all of my 2006-2007 Sixth Grade
students who helped me improve my Powerpoints
You helped me with:
o Pictures for backgrounds
o Better font
o Animation
o Figuring out what works or doesn’t
o I still have a long way to go
22