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The geographical features that make New York stand out from any other of the United States--Long Island, the huge boulders scattered in the city and the Hudson River, deep enough for barges to pass through without problem--are possible because New York was the furthest south that the ice of the Late Pleistocene extended from the Arctic.

enter image description here

Now, in this alternate ice age, lobes of ice extended further southwards, to Washington DC, Virginia and Chesapeake Bay. Would we still find the distinctive shape of Long Island? Or would the more extensive ice alter the geography of the New York cityscape?

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  • $\begingroup$ Reminder to close-voters... $\endgroup$ – Frostfyre Jul 28 '16 at 12:15
  • $\begingroup$ Any reason why you're thinking of closing this BEFORE answering it? $\endgroup$ – JohnWDailey Jul 28 '16 at 13:26
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    $\begingroup$ @JohnWDailey Why would someone answer a question AND then vote to close it? This question (and the series in general) feel on topic to me but I don't know that you are going to find anyone with the knowledge to answer your questions...if such people even exist. I am pretty sure you should just be deciding stuff like this on your own. You are altering your world at a very fundamental level and the short answer to each of these questions is... no one knows As a suggestion I would steer away from these alternate reality geography questions but that is up to you. $\endgroup$ – James Jul 28 '16 at 13:49
  • $\begingroup$ Reminds me of The Day After Tomorrow. $\endgroup$ – Renan Jul 28 '16 at 20:51
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    $\begingroup$ @James, dude, the whole point of this site (to me) is to fire the imagination with interesting questions. This is an interesting question, one that is worth my time to research and try to answer (not that I have one...yet). Why would you dissuade people from asking questions that are difficult to answer? Also, to specifically rebut you, I am very interested in the alternate geography of North America, certainly more than that stupid anatomically correct series. Don't stick your value judgments on someone else's question. $\endgroup$ – kingledion Jul 29 '16 at 14:37
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Well, if the glaciation is deeper and/or longer lasting, there's probably still going to be a glacier coming down the Hudson River valley. Sea level was considerably lower at the time, and the grinding action of the glacier is likely to deepen the valley.

So by our time, with the sea level approximately where it is now, the mouth of the Hudson may well be further North, with a bay where Manhattan is now. This is only general reasoning about glaciers and sea levels: I have no knowledge of the geology of the area.

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It would depend on how far your ice sheet would move southward and how far onto the continental shelf the ice extended. For example would the Outer Lands still be there or moved further south. Conceivably Long Island would be smaller as it would be further out on the Continental Shelf.

Outer Lands

There may be a restriction on the shape of newly imagined Long Island due to the Hudson Canyon.

Hudson Canyon

New Long Island could be split into two, or New Jersey gets a terminal moraine peninsula and a smaller Suffolk Island out in the ocean.

Looking at your question I started to imagine the Hudson or Delaware River getting damed up just like the Missoula Floods and then realized that the East Coast doesn't have the mountainous valleys of the West which would allow for ice dams and subsequent catastrophic floods.

So just get a topographical map of the East Coast (along with the continental shelf drop off). Figure out where the new ice sheet stops, and move the real world terminal moraine over to your new spot and see what pops up above sea level.

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  • $\begingroup$ Like I said, we have lobes stopping through Virginia, Washington DC and Chesapeake Bay. $\endgroup$ – JohnWDailey Jul 29 '16 at 5:36
  • $\begingroup$ Unclear how the lobes which don't drain into New York would affect New York geography as stated in your OP. $\endgroup$ – Morrison Chang Jul 29 '16 at 5:51
  • $\begingroup$ I don't understand how this could be unclear. $\endgroup$ – JohnWDailey Jul 29 '16 at 5:54
  • $\begingroup$ What I mean is that New York geography wouldn't be affected by additional glacier lobes not in the watershed of New York. If you are asking how would Virginia, DC and Chesapeake Bay be affected by such an ice age - well that wasn't your original question. Also you don't specify where the glacier lobes go - which is rather like trying to build a house on a piece of land that is half swamp and half rock with a location of 'over there'. $\endgroup$ – Morrison Chang Jul 29 '16 at 6:01
  • $\begingroup$ How did you mean by specifying "where the lobes go"? $\endgroup$ – JohnWDailey Jul 29 '16 at 6:15

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