GLACIAL LAKE ALGONQUIN. 441 



The first St. Clair beach is scarcely traceable along the river front in Detroit, but it crosses 

 Jefferson Avenue about a quarter of a mile west of the waterworks as a faint wave-cut bench 

 with no noticeable cliff and then turns away inland. It runs thence a little east of north to 

 Mount Clemens and thence northeast for about 10 miles and fades hi to an ill-defined sandy 

 belt on the clay plain north of Anchor Bay. It lies 2 to 4 miles back from the present shore of 

 the lake for its whole course except 2 or 3 miles along the bay north of Mount Clemens, where 

 it is not over 1 mile back. In this part it is stronger than common and has a well-defined lake 

 cliff at its back 3 to 7 feet high. An island which at the time of this beach reached northeast 

 for about 2 miles from Grosse Pointe is about half a mile wide and, in a small area on the Moran 

 road at its western edge, rises to 620 feet above sea level and is capped with gravel which, from 

 its altitude, appears to belong to the Lundy beach. The first St. Clair beach runs through the 

 village, generally an eighth to a quarter of a mile from the shore, in the form of a low beach 

 ridge of gravel. A gravel spit rising a little above the general level of the beach runs 70 or 80 rods 

 southwest from the southwest end. 



Grosse Pointe Island was separated from the mainland to the west by a trough the lower 

 part of which is half a mile wide and swampy. This runs through from Milk River at the 

 north to the flats of Fox Creek a mile southwest of the village and is now only 5 or 6 feet above 

 the lake. It is floored with several feet of lake clay and was therefore originally somewhat 

 deeper. 



The island is distinctly morainic and the shore all along its front is paved with bowlders. 

 Three miles to the south the lighthouse at Windmill Point stands on a small isolated fragment 

 of bowldery till, probably part of the same moraine. 



On the south shore of the lake 25 miles east of Windsor, Ontario, the land projects into the 

 lake in a wide blunt cape called Stony Point. Its shore is bowldery and suggests morainic 

 ground, but the flat land of that vicinity does not indicate its course and no detailed studies 

 have yet been made in that region. 



On the Canadian side the first St. Clair beach has not been traced. The country surface 

 is very low and flat to the south and east, indicating a much wider interval between the old 

 beach and the present shore. The altitude given on the Canadian official topographic maps 

 indicate a line passing east from Walkerville 2 to 3 miles back from the shore, the distance 

 increasing eastward. It passes a mile north of Comer and 2 miles south of Tilbury. Five 

 miles east of Tilbury this fine is slightly nearer to Lake Erie than to Lake St. Clair. Along this 

 line nearly all the streams show jogs indicating some diverting influence, such as would be 

 exerted by a beach. Thence the probable course, as indicated by the altitudes, passes a few 

 miles west of Chatham and a little east of Wallaceburg and to St. Clair River a few miles 

 south of Courtright. On such flat ground the beach would be likely to be merely a low belt of 

 fine sand. Several fragments of tliis sort have been observed west of Chatham and toward 

 Wallaceburg but have not been traced connectedly. 



The basin of Lake St. Clair is simply an intermorainic trough or original depression in the 

 drift lying between the mam moraine of the Port Huron system on the north and another moraine 

 which passes through Detroit and Windsor and along the north side of Lake Erie from near 

 Leamington. It is probably accidental that the lowest point on the Detroit moraine was at 

 Detroit instead of at some point farther east, as near Tilbury, where it would be more centrally 

 located with reference to the axis of the Lake Huron glacial lobe. 



The greatest depth in Lake St. Clair is 22 feet. Its surface at present has an altitude of 575 

 feet above sea level. At the time of the highest Algonquin beach (Early Lake Algonquin), 

 its altitude was 595 feet, or 20 feet above its present level, and at the time of the Nipissing 

 beach its altitude was 587 feet, or 12 feet above its present level. Lake St. Clair came into 

 existence at the same time as Early Lake Algonquin. 



