glaciers once covered most of the Earth –in total there have been up to 22 times when glaciers covered large areas of the Earth… including Alberta the Earth is currently in an ice age that began over 2 million years ago –since ~ 1850 glaciers have been retreating Glaciers

Rivers of Ice –move very slowly… –they can take a year to move as far as you can walk in a few minutes –a fast glacier might move at 1 m per day

two types of glaciers –alpine glaciers form in mountains –continental glaciers form in polar regions (Greenland, Antarctica, Arctic) there are glaciers on every continent (except Australia)

How do glaciers form? glaciers are made from compressed snow (not frozen water) a glacier forms when more snow falls in an area during winter… than melts in the summer when there is more snow accumulating than melting the glacier grows… when there is more snow melting than accumulating the glacier shrinks

accumulation zone: where the snow accumulates ablation zone: where the snow melts equilibrium line: where snowfall = snowmelt

glaciers are born in cirques: steep-sided, bowl-shaped areas where snow collects when a glacier runs into the ocean or a lake, ice can break off forming ice bergs… this process is called calving

On The Ice the surface is not smooth where the ice ‘bends’ over uneven ground it cracks & forms crevasses

Glaciers have sculpted our landscape without glaciers our mountains would be mostly rounded domes Horn Aréte

ridges of rock and dirt called moraines are left deposited along the edges of the ice Glaciers are like giant conveyor belts… transporting rock and dirt on & in the ice lateral moraine medial moraine terminal moraine

glaciers also deposit tones of material in outwash plains across the bottom of the U- shaped valleys and water from glaciers form braided streams that carve river valleys, transport sediments and fill lakes

drumlin: a pile of debris left behind as the glacier receded erratic: a large boulder carried a long way by the ice, and then deposited Direction of Ice Flow Morley Flats Okotoks Erratic

kettle lakes: lakes left by the melting of smaller blocks of ice esker: a ridge of gravel left where a river ran under the ice

Glacier Present After Glacier Melts Glacial Landscape

Glacier Present After Glacier Melts

glaciers are retreating… mainly caused by global warming moraines can tell us where ice once was once glaciers are gone the world will have much less freshwater… and sea levels will rise What is the Future?