450 PLEISTOCENE OF INDIANA AND MICHIGAN. 



that shows unconformity will be found. Whei-e 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, they are as a rule heavier and less sandy than those 

 below the Nipissing. Only where the Nipissing derived fresh material from the cutting of some 

 great bluff or from outcrops of limestone or shale is it likely to be as pebbly or gravelly as the 

 Algonquin. 



On certain shores the Nipissing beach has been largely and in places almost whoUy cut 

 away at present lake level. This is notably the case along the east side of the "thumb" north 

 of Port Huron, on both sides of Lake Michigan, and on the east side of Lake Huron. 



DISTRIBUTION IN MICHIGAN. 



Port Huron to Port Austin. — The shallow embayment between Port Huron and Lakeport 

 has a faint Algonquin beach at its back and a stronger one a mile farther out. Outside of 

 these the Nipissing and lower beaches complete the filling of the old bay and bring the shore 

 to a straight line. 



About a mile north of Fort Gratiot a sandy bench appears in front of the Algonquin. It 

 extends north, widening within 2 miles to a mile and continuing with this width for about 3 

 miles, to about half a mile south of Lakeport, where the present lake has cut it away. The 

 outer part of this bench is mostly slightly below Nipissing level, but back from the lake it rises 

 gradually to the base of the Algonquin ridge. So much of it is close to the Nipissing level 

 that it is presumably mainly of that age. Almost the whole bench is covered with fine sand, 

 much of it wind blown and heaped into small dunes. 



Northward from Lakeport the Nipissing beach has been cut away for many miles. What 

 is possibly a very small remnant of it appears just south of Stevens Landing, 6 miles to the 

 north; but from there northward it is gone for over 40 miles, or to a mile north of White Rock. 

 From its beginning north of White Rock to the mouth of Cooper Creek, 3 miles north, the 

 Algonquin beach has been cut away by the Nipissing waves, but beyond that both beaches 

 are generally present and the Nipissing beach is substantially continuous around the remainder 

 of the "thumb" and Saginaw Bay to Au Sable River. 



Throughout this stretch the Nipissing beach is conspicuously developed in few places. 

 For short distances it cuts into the Algonquin beaches and thus shows distinct discordance, 

 and for a few very short distances it is cut away by the present lake. One such cutting appears 

 about 3 miles southeast of Huron on the outer part of the "thumb." Farther on, near Grind- 

 stone City, at Pointe aux Barques, and near Port Austin it is cut away for short distances. 



Port Austin to Bay City. — Between Port Austin and Caseville the Nipissing beach is so 

 much obscured by dunes that it is not easily distinguished. Between Caseville and Bayport 

 it is mainly sandy, but at some points is a ridge of pebbles and shingles. From Bayport past 

 Sebewaing to Quanicassee it is generally a gravel ridge or group of ridges of nearly the same 

 height. For several miles east of Essexville also it is gravelly. 



Bay City to Au Sable River. — From Bay City northward past Lengsville to Saganing, 

 where the hinge line of the Algonquin and Nipissing beaches crosses the west shore of Saginaw 

 Bay, the Nipissing beach is a belt of sandy ridges half a mile to a mile from the lake shore. 

 A mile or two north of Alabaster the cliff back of the beach is 60 to 70 feet high and the bench 

 a quarter of a mile wide. The beach is a wave-cut bench that carries ridges to the mouth of 

 Tawas River. Thence through Tawas and East Tawas and beyond to Au Sable River it is a 

 low, broad ridge or belt of sandy, gravelly ridges half a mile to a mile wide. From East Tawas 

 it lies generally about a mile back from the shore. An extensive swamp behind it stretches 

 6 or 7 miles northeast from Tawas Lake. 



Au Sable River to Mackinaw City. — At Alabaster and Tawas the vertical separation of 

 the Algonquin and Nipissing beaches has noticeably increased, and it continues to increase 

 slowly northward to Alcona. Between Devil Lake and Presque Isle it increases more rapidly. 



