Nipissing Great Lakes
Nipissing Great Lakes was a prehistoric proglacial lake. Parts of the former lake are now Lake Superior, Lake Huron, Georgian Bay and Lake Michigan. It formed about 7,500 years before present. The lake occupied the depression left by the Labradorian Glacier. This body of water drained eastward from Georgian Bay to the Ottawa valley. This was a period of isostatic rebound raising the outlet over time, until it opened the outlet through the St. Clair valley, at one stage it had two stable outlets both draining to the east.
Origin
The Lake formed from the aggregation of Glacial Lakes Houghton, Chippewa and Hough, and Stanley as water levels increased. Levels returned and Lake Chippewa again flowed through the canyon at Mackinac until around 7,500 YBP. At that time, the waters in the Michigan basin, Huron basin, and the Superior basin created a single lake encompassing all three of the upper Great Lakes. The lowlands through the rapids of Sault Ste. Marie and across the Upper Peninsula of Michigan were open bodies of water.Location and area
The term "Nipissing Great Lakes" is applied to the waters of the upper three Great Lakes during the stage. The glacier had receded completely from the Great Lakes Basin. The plural form is used to denote that each basin was a separate unit, with a narrow strait connecting each. Each basin stood at the same elevation and thus appear as a single body of water. Lake Michigan connected to Lake Huron by the Mackinac strait, except the water was higher. There was also a narrower, shallower channel Little Traverse Bay to Huron basin. The outlet of the lakes, however, was eastward from the northeast angle of Georgian Bay.Outlets
The North Bay Outlet was at North Bay, Ontario, the modern Lake Nipissing. As the ground continued to rebound from the weight of glacier, the Port Huron outlet began to again receive water, creating a temporary two-outlet lake.1st Ottawa">Ottawa River">Ottawa & [Mattawa River]
The North Bay outlet river, or " Nipissing-Mattawa River," crossed an area of crystalline rock, chiefly gneiss, reaching the Mattawa River, which joined the Ottawa River at Mattawa, which led out the St. Lawrence to the ocean. Mattawa River is a chain of lakes. Some of the lakes are long, narrow, and deep, lying in canyon-like valleys to wide, with water to deep. The canyons are or more high. A few places along this route show a scoured bed that would require a similar volume and velocity of water movement as St. Clair River today.2nd Detroit & Port Huron
In the early part of this closing two-outlet stage a small discharge went by way of Illinois River at Chicago. The basin there is only and the Nipissing beach is above the modern lake. The small discharge would have ended when the outlet at Port Huron had cut down or.Beaches
The low water beaches were submerged through most of their range as the land rebounded. Thus, the known beaches of the Nipissing Great Lake are those formed during the period that the St. Clair valley served as the outlet. Only a few of the older beaches survive. Lake Nipissing, like Lake Algonquin, is reflected in the character of the channel in the Niagara Gorge. A part of the gorge at the whirlpool and a small section above and below it shows a shallow excavation both sides. This shallow excavation was made by a weak waterfall when the Erie basin was the main watershed feeding falls. Near the suspension bridges a deep excavation begins which extends up to the present cataract. This seems to have been created since the flow from Lake Nipissing turned into the St. Clair outlet, feeding water to Lake Erie. The rate of recession the falls would require between 2,700 and 3,500 years to make the deep part of the gorge.Since the opening of the St. Clair outlet there has been continuous flow in the present direction, and the outlet has suffered a slight deepening which has lowered the lake level perhaps. The beach at in the southern end of the Huron basin seems to have been occupied by Lake Nipissing as well as by the late stage of Lake Algonquin, so the lowering of the lake is from that height to the present. The present beach is to with a mean stage of water about.
Nipissing Beach
The name "Nipissing beach" has from the first been applied to the shoreline formed during the two-outlet stage of the lakes. The name more precisely belongs to the older beach made by the Nipissing Great Lakes when the whole discharge passed through the Ottawa River.After the formation of the true Nipissing beach isostatic rebound elevated the region. This lowered the water plane on the north side of the basin and raised it on the south side. Thus the beach from the earlier stage of the Nipissing Great Lakes in the south was flooded and destroyed. Only the area in the northeast corner of Lake Superior still retains remnants of this first or original Nipissing beach.
The point of elevation or the ‘hinge line’ for Nipissing beach is the same as the highest Algonquin beach. South of the line the Nipissing beaches are horizontal and vary between above the present lake level, the mean being.
In the south, the Algonquin beach and the Nipissing beach can be indistinguishable. Both are from below the Algonquin high beach. Where the Algonquin divides into several ridges, the Nipissing beach will be one these ridges. In the Superior basin where any considerable width of beach deposits intervenes between the Nipissing and the present shore it is likely to be occupied by rather light beach ridges set very close together, with the Nipissing beach as the uppermost. Where the Algonquin is represented by several ridges, the Algonquin beaches are heavier and less sandy than the Nipissing. Along the east side of the Michigan ‘thumb’ the Nipissing beach has been cut away by the present lake. This is most noticeable along the east side of the "thumb" north of Port Huron, and on both sides of Lake Michigan, and on the east side of Lake Huron.