34 SEVENTH REPORT. 



(2) Spring Hill is on a spit of the Belmore beach at the entrance to Black River valley. 

 East from Spring Hill to the crest of the moraine east of Black river is a distance of about 

 three and a half miles. The long bay which lay to the north at that time may be called 

 Black River bay. The Arkona beaches show their modified, low relief up to the mouth, 

 of this bay. But to the north, where they lay on the floor of the bay, they grow rapidly 

 stronger with full relief and lighter soils, like other beach ridges which have not been 

 modified by submergence. In the bay area they average ten to twelve feet in height. 

 The lower ridge may be traced six and a half miles north from the road running east from 

 Spring Hill. In the last two miles this ridge is cut away by the river in four places. Two 

 fragments of it occur on the east side of Black river, the first one being about forty rods 

 long and the second about twice this long. A third short fragment farther up the valley 

 is on the west side of the river. Both of the fragments on the east side are in actual contact 

 with the front of the Port Huron moraine. Its foot rests directly against the east side 

 or face of the beach ridge in both cases. Within ten paces one may step from the loose 

 gravelly soil of the beach ridge to the hard, stony clay soil of the moraine. These frag- 

 ments of the beach are developed in full strength and, contrary to reasonable expecta- 

 tion, bear no appreciable amount of out wash, although the moraine is so close and rises- 

 to the height of sixty feet or more in less than half a mile to the east. 



The middle ridge rims fourteen and a half miles nortli from tbe 

 Spring- Hill road and the upper ridge seventeen and a half miles. Both 

 keep their full strength to the end and show no modification due to sub- 

 mergence. Both are finally lost by being buried under sandy ontwash 

 from the moraine, the middle ridge at a point one mile northwest of 

 Croswell and the upper ridge one and a half miles south of Applegate. 



The occui-rence of strong beaches in the bottom of a valley facing 

 a great morainic ridge so close to them, one of them being- in actual con- 

 tact with it, is a very unusual arrangement. In their present relations 

 there is no open lowland or bas^in in front in which waves could have 

 gathered to form beaches, for the moraine rises to higher levels than thev 

 do. 



There appears to be but one explanation. Neither the moraine nor 

 the ice which made it were there when the beaches were being built. 

 Instead, there must have been a wide expanse of open water in front, the 

 ice front at that time being many miles away to the north and north- 

 east. The remarkable preservation of the beaches north of Spring Hill 

 appears to be due to the fact that they were submerged in a shallow 

 bay which had a narrow mouth and which on this account protected 

 them from the heavy seas which effected the same ridges so greatly in 

 the open lake area south of Spring Hill. It was a re-advance of the ice 

 after the Arkona beaches had been made that brought the moraine into 

 the place where we now find it, close in front of the beaches, and the same 

 re-advance brought Lake Whittlese}- into existence after the Arkona 

 beaches had been formed. The result was that the Arkona beaches 

 were submerged under Lake Whittlesey, and while they were almost de- 

 stroyed in the area south of Spring Hill, they were protected and pre- 

 served in the Black Eiver valley. 



(3) In the Saginaw valley certain strong, gravelly beach ridges, usually two or three 

 close together, have long been a puzzle as to their identity. Spencer thought they belonged 

 to his Ridgeway beach which is now called the Belmore. Later, they were thought to 

 belong to the Forest beach, and still later they were called the Saginaw beaches, and 

 were supposed to belong to Later Lake Saginaw alone. But last year's work shows that 

 they are in reality the Arkona beaches in an area where they have not been submerged 

 or modified in any way. Their position next above the Forest beach confirms this identi- 

 fication, -prhese ridges in the Saginaw valley are composed of gravel, are strongly developed 

 and are in'feverv way fully comparable with the unmodified Arkona ridges in the Black 

 River valley. The Port Huron moraine from Vassar to Cass City makes the ^'alley of Cass 

 river a long, oointed bay at the Arkona level, shallow and narrow at its head. Yet the 



