Some Great Lakes visuals needed

[Barcode]

Heya,

Not having been to the Great Lakes region much...except driving to Milwaukee for GenCon a few times, I am at a loss on how to visualize the next part of my campaign.

The very short version is that it is in the future, several millennia from now, and that things have transpired to explain magic and the loss of technology.

I want the Great Lakes to be a larger, more throroughly navigable freshwater sea, (i.e no canals/locks). There is also an ancient plot point whereby several ancient cities were wiped out by powerful mages by essentially flooding Lake Michigan.

My thought is to basically dam up the Detroit River (with a colossal, epic, magically created dam), raising the level of Lake St. Clair, Michigan and Huron about 22 ft, making it level with Superior, turning the St. Clair River into a strait, creating some archipelagos where the lakeside is hilly, and who knows what else.

Some questions... How hilly are the Michigan peninsulae (upper and lower)? How steep are the shores? The Ontario shoreline? If I raised the level of the lake 20ft, how far inland would the floodwaters go? How wide would the Detroit River get (i.e. how wide would the dam need to be)?

In the area around Sault Ste. Marie, what is the nature of that waterway? Narrow and fast? Wide and slow? Gorges? Superior is 601ft above sea level, Huron and Michigan are 579ft, so if I levelled the two, what would this look like? A narrow strait, or would the floodwaters extend much further inland?

Taking the same concept further, if I put my colossal dam at the mouth of the Niagara River, I could conceivably raise Lake Erie 31ft. So what would that do to Ohio and Ontario? I remember Ohio's shoreline being pretty flat, so presumably I would widen the lake by several miles. How wide would the Niagara River get near it's source?

Thanks for your input...

-B-

 

[Vrecknidj]

Some questions... How hilly are the Michigan peninsulae (upper and lower)? How steep are the shores? The Ontario shoreline? If I raised the level of the lake 20ft, how far inland would the floodwaters go? How wide would the Detroit River get (i.e. how wide would the dam need to be)?

In the area around Sault Ste. Marie, what is the nature of that waterway? Narrow and fast? Wide and slow? Gorges? Superior is 601ft above sea level, Huron and Michigan are 579ft, so if I levelled the two, what would this look like? A narrow strait, or would the floodwaters extend much further inland?

Taking the same concept further, if I put my colossal dam at the mouth of the Niagara River, I could conceivably raise Lake Erie 31ft. So what would that do to Ohio and Ontario? I remember Ohio's shoreline being pretty flat, so presumably I would widen the lake by several miles. How wide would the Niagara River get near it's source?

Thanks for your input...

-B-

A few answers (sorry I can't answer more). . . .

I've lived in Michigan since the early 1970's, and I've visited in or worked in much of the state.

The upper peninsula is far hillier than the lower peninsula--it even contains regions that would amount to very small mountains. In addition, there are several very large mineral mines there (interesting plot items perhaps--lay lines, portals, who knows). Also, in the U.P., there are regions that have tremendous amounts of snow, similar to Buffalo, NY (i.e. snowfall measured in feet instead of inches is common in a typical winter).

Up by Sault Ste. Marie, the waters are usually not so bad, but there's a stretch, about three-quarters of a mile long, that's very rapid and very dangerous. In that area the level of the river drops about 20 feet. I suppose that thousands of years plus a little magic could turn this into a falls area not unlike Niagara.

The southern region of Michigan, and the northern regions on Indiana and Ohio, are very flat--there are locally hilly regions, but as a rule they're quite flat. But, there are also tons of rivers around here. If the Great Lakes were to somehow be made lower, or the region flooded, the rivers could carry a great deal of this away. Of course, this might just change the whole eastern midwestern region.

But . . . In Michigan, it's not possible to travel more than about 5 miles without hitting a body of fresh water (most of them are small lakes, perhaps a mile or so in diameter). There are lakes everywhere around here. And, the water table is quite extensive. Pretty much anywhere in the state you can drill a not-too-deep hole and hit a large body of water suitable for irrigating a field or providing drinking water for a fair number of people. Given these facts, it's entirely possible that the whole area could be turned into a freshwater sea (or, perhaps, into a bay, not unlike Hudson Bay extending northeast up towards Montreal).

Dave