GLACIERnatural accumulation of land ice

showing movement at some timegreat ice sheets have waxed and waned

over the surface of the Earthcauses for the increase and decrease in

ice sheets are still uncertain, probably not one single thing

http://www.pbs.org/wgbh/nova/vinson/glac-nf.html

CAUSES OF GLACIATIONCLIMATE CHANGEEarth has experienced many climate changeschange in Earth temperature and air/water

circulationdecrease of  4o to 5o C (especially summer) large increase in the amount of snowfall in

subarctic and arctic regions

SUGGESTED THEORIES FOR CLIMATE CHANGEreductions in solar radiation due to meteorite

collisions with the Earth, increased volcanism shifting location of continentsuplift of vast mountain regionsMilankovitch Cycles

MILANKOVITCH CYCLESMilutin Milankovich – Serbian Astrophysicistthought to cause the necessary change to

decrease global temperatures. Earth's orbit is elliptical, over periods of 100,000

years the shape varieschanges in orbit have been matched with ocean

sediments that record the history of glacial stages

cycles of warming and cooling match with the estimated dates of glacial periods

Earth "wobbles" on its axis which alters the amount of solar radiation reaching the Earth

Ice Sheet Structurezone of accumulation, the portion of the

glacier over which accumulation exceeds ablation

zone of ablation is the loss of ice (or snow) from the glacier

equilibrium line is the boundary between these two zones

If accumulation > ablation the glacier will growIf ablation > accumulation, the glacier will

retreat

Ice Sheet Structure

Continental Form on continents, flat land

Ellesmere Island, Canada

Global distribution of continental glaciers

AlpineForm in mountains

Jungfrau, Switzerland

Nisqually , Mount Ranier

PiedmontForm by combining of alpine glaciers

Malaspina Glacier, Alaska (landsat)

Switzerland

IcebergsPieces of glaciers that have

broken off into water.Do you know what this

process is called?

Glacier Bay , Alaska

Ablationsublimation - solid to gas, ice (firn) to water

vaporwind erosion – just like sand blowing away on

a beachmelting – ice changing from solid to liquid

formevaporation - liquid to gascalving – process of glaciers breaking off into

bodies of water, produces icebergs

Sublimation

Ablation on Glacier de Tsanfleuron, Switzerland

Calving

What makes glaciers melt?List at least 3 things in your notes

REFERENCES http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/glacial_systems/glaciation_causes.html http://www.worldviewofglobalwarming.org/pages/glaciers.html http://www.commondreams.org/headlines02/0925-05.htm http://www.space.com/scienceastronomy/planetearth/pumpkin_planet_021205.html http://www.uwsp.edu/geo/faculty/ritter/geog101/uwsp_lectures/lecture_glacial_processes.html http://www.swisseduc.ch/glaciers/glossary/ablation-en.html http://www.pbs.org/wgbh/nova/vinson/glac-nf.html http://www.swisseduc.ch/glaciers/glossary/ablation-en.html