GLACIAL LAKE WHITTLESEY. 379 



the valley from the gateway at Spring Hill to the vicinity of Croswell and Applegate. West- 

 ward from this was a wide flat in which the water was shallow, and west and north of the drift 

 ridges which obstruct the valley at Buel, 3 miles west of Applegate, shallow water of narrower 

 width stretched away to the head of the bay at Ubly. The greatest width was not over 7 or 8 

 miles, and the average was not over 3 or 4 miles. In times of southerly or southwesterly gales 

 on Lake Whittlesey heavy seas entered the gateway and rolled up the axis of the deeper trough 

 with comparative ease. The Whittlesey bars, which stand close to the western edge of the 

 trough — the one 2J miles west of Amadore and west and southwest of Applegate — are particu- 

 larly strong. But the waves could not turn abruptly westward with much force over the wide 

 flats northwest of Spring Hill and were so weakened there that they did little work. All along 

 the trough the waves that ran out over the flats to the west were slackened and deflected into a 

 westward or northwestward course and were relatively feeble where they struck against the 

 land at the west side of the flats. Thus the work done in this valley at the time of Lake Whit- 

 tlesey appears to have been accomplished almost entirely by waves coming from the southeast 

 or east. As all Whittlesey bars in this valley are in the shallow area west of the trough, it is 

 entirely natural that the effects of wave work should be placed as they are, facing east or south- 

 east. Although the waters reached for many miles north and northwest they were very shallow, 

 and although the gales from that direction are more frequent and prolonged than those from the 

 south they caused no effective wave action. 



In view of the remarkable preservation of the Arkona beaches in the Black River valley 

 north of Spring Hill, it is very significant that careful search over the westward slope of the main 

 moraine of the Port Huron system on the east side of Black River has revealed no corresponding 

 beach ridge nor other wave-made features. A few small gravelly or sandy outwash deposits from 

 the ice, made apparently at the level of Lake Whittlesey, are all that appear. Manifestly, the main 

 moraine of the Port Huron system, or rather the ice mass which deposited it, constituted the east 

 side or bank of the trough up which the waves ran into the Black River Bay of Lake Whittlesey. 

 As the moraine was built by ice which advanced to the position of the moraine and did its work 

 after the formation of the Arkona beaches, it could not bear any record of those beaches on its 

 front. But during the time of Lake Whittlesey the moraine and the ice which was building it 

 were standing there, and the moraine might be expected to bear at least a few faint evidences of 

 wave action. Evidently, however, either the ice itself formed the shore, or readvance of the ice 

 or outwash or the erosion of streams issuing from the ice obliterated the marks that the waves 

 produced on the face of the new moraine. The remarkable immunity of the whole face of 

 this moraine from all the wave action that affected the shores on the west side of Black River 

 is evidence enough that the building of the moraine marks an epoch in the history of the lake 

 waters. The ice lobe pushed rapidly southward, overriding and destroying the beaches that 

 lay in its path and setting definite limits to those that it left and to those that were made while 

 it held its place. 



It would hardly seem possible for those who doubt the reality of the land ice sheet and its 

 great function as a dam or barrier, retaining lakes as large as those here described, to resist the 

 power of such facts as these. Evidently, before the ice could move up the slope out of the basin 

 of Lake Huron to the position of this moraine it must have been solid; and if it came from the 

 north or northeast it must have filled the entire basin of the lake. In order to flow toward its 

 edge and drive its basal parts up the slope it must have been higher over the central part of the 

 basin than around its edges, and such an ice mass capable of transporting and depositing such a 

 body of drift as the Port Huron system was surely competent to be the retaining barrier of Lake 

 Whittlesey. 



All of the facts displayed in the Black River vallej 7 are completely in harmony and are in 

 perfect accord with the idea that the Arkona beaches were made first and extended northward 

 around the "thumb" into the Saginaw basin, and that the ice sheet then reaclvanced to the posi- 

 tion of the main moraine of the Port Huron system, destroying the Arkona beaches on the 

 "thumb," drowning all those south and east of it, and causing the formation of Lake Whittlesey 



