Would the resulting fresh water drain into the ocean, or would the melting result in a vast freshwater lake? I read that the 1-mile think icecap has depresses the interior of the island, to a point below sea level. So would Greenland become a big lake, hemmed in by the coastal mounta ranges?-or would the water drain off, and the land begin rising? Much of New England was covered by ice (the Laurentide Ice cap) during the last Ice Age-and the melting of this ice produced a huge lake (lake Hitchcock)-how long did this persist for?
The Greenland Ice Cap is domed in the middle, so that most of the melt would be expected to run into the sea. There could, however, be local areas where freshwater lakes could be impounded.
Although the center of the island is depressed below sea level by the weight of the ice, even if all the ice melted this would not form a permanent freshwater lake since there are low spots around the perimeter that would permit sea water to enter. You would intially have a fairly fresh lake, becoming brackish as sea water entered the basin, and finally equilibrating with the seas once all the ice was gone.
I always thought the Connecticut River Valley [stretching from coastal Connecticut all the way up to Canadian border] was carved by receeding glaciers. Is this the same thing?
As for your OP, are you asking if coastal regions would be effected? Like eventual leveys and dikes around NYC?
And eventually – meaning on the order of tens of thousands of years – the depressed central area would rebound from the removal of the weight of the ice, and rise above sea level.
From core samples, this is precisely what appears to have happened in the Baltic. Before the Ice Age, hiking from the futures sites of Hamburg to Stockholm to Riga, though a good long journey, would have been possible on a straght line course (well, two, with a jog in the middle at Stockholm). There’s an obvious issue with that today.
And the Baltic appears to have been a freshwater lake impounded by ice dams when it first formed from ice melt. Thereafter it moved in a brackish direction, though due to riverine inflow it’s never gotten to equilibrium with the ocean. And it’s becoming shallower on a order-of-a-millimeter-per-year basis, as the depressed sea floor slowly seeks equilibrium by isostatic rebound.
Actually, I was reading about this a few months ago. The Connecticut River Valley is much, much older than the last glacial period which ended about 10,000 years ago.
The Connecticut River Valley is actually a “rift valley.” It was created when the Pangaea supercontinent began breaking apart about 250 million years ago. At the time, Connecticut was located in the interior of the supercontinent. When the supercontinent broke apart, one of the faults went right through the center of what is now Connecticut. The enormous forces involved in the stretching of the fault created a depression that resulted in a rift valley. (Of course the continents actually ended up separating farther to the east.)
Anyway, since the Connecticut rift valley was a low point, it’s natural that a river would end up in the same location. However, neither the river nor the glaciers created the valley. Plate tectonics did the job hundreds of millions years earlier.
There’s some info about this here:
http://homepage.mac.com/ebandpck/cityrocks/connecticut.html
Here’s another link with more info:
http://www.earthview.pair.com/ctriver.html
This site puts the beginning of the Connecticut rift at 225 million years ago.