2011 2: Great Lakes Intro Flashcards
How big is a great lake
over 500 square km
how many great lakes world wide
250
How many of the GL are in Canada
1/3
The Laurentiant great lakes are
named because they come from where the Laurentiant ice shield was: Superior, Huron, Michigan, Erie, Ontario
Watershed
of the great lakes is 295,000 square miles or 764, 051 square km
Shoreline
of the great lakes - shared with the US: 12, 100 miles (20,2007 km) in total
6850 miles in ON and Quebec, 5270 miles in 8 US states
Drainage
The great lakes drain east from Lake Superior and Lake michigan, through Lake Huron and Lake St Clair, Lake Erie then over Niagara Falls into Lake Ontario to the St Lawrence and the Atlantic Ocean
Chicago River
once flowed into the very shallow Lake Michigan and it carries all of the crap from the cities waste and due to the long arm and constant waves the pollution built up rapid = problems. Flow was the reversed into the Mississippi as a sanitary cannel - a portion of the river is electrified because of the invasive species
Agreement in the great lakes basin?
that the water should stay in the watershed that it was taken out of!
What terms are interchangeable?
watershed and basin
Characteristics of the GL
contain 23,000km^3 of water in an area of 244,000 square km, it is the largest system of fresh surface water, consists of 18% of the worlds fresh water supply
Outflows (water leaving the system)
less than 1% a year, therefore pollutants that enter are retained in it for a long time!
Salt water
97.5%
Fresh water
2.5%
Out of the 2.5% of fresh water
ground water 30% and polar regions and glaciers are 69%, and rivers and lakes are 0.12%
What is the problem with the glaciers?
the glacier and polar regions are melting and melting the fresh water supply into salt water!
Why is ground water concerning?
because we don’t know what it has picked up: we don’t know what pollutants it has / how clean it is
fresh water
surface fresh water is rare and we have more of it than anyone
How were the GL formed? Wisconsin Period
began 70,000 years ago, ice picked up clay/sand/gravel/boulders, as the ice melted it moved and shaped the landscape, it withdrew 14,000-15,000 years ago, the massive meltwater created the ancestral lakes
the clay/sand/gravel/bounders formed hills, ridges and moraines
Evolution of the Great Lakes System
the shape of the great lakes is always changing and it has evolved due to: retreat of glaciers, topography surrounding the lakes, gradual tilting of the earths crust (major factor since glaciers retreat), also all the stuff that water natural does: erosion.etc
ongoing evolution of the great lakes
what three things?
crustal tilting, shore erosion, climate change = these three things continue to alter the shape and size of the great lakes
what happens when the weather is warmer
there is more evaporation in the summer and more in the winter if the lakes do not freeze over causing more movement of water
what has a large impact on the lakes?
the land surrounding the lake
depth?
superior = very deep, erie = in comparison is a puddle its so shallow!
