42 F. B. TAYLOR — CORRELATION OF BEACHES AND MORAINES. 



southwest, and the two form a sharply defined angle of 75 degrees. The 

 high ridges of the two moraines do not unite, but are cleft just in the 

 angle. A small brook, the head-waters of Willow river, drains a part of 

 the gravelly channel bed at the extreme north angle of the bend and 

 carries its waters away north through the narrow gap to lake Huron, 

 near Grindstone City. This cleft probabty marks the entrance of a small 

 glacial tributary to the great outlet river flowing from the ice-sheet when 

 its front rested close by on the main moraine. The bend of the channel 

 is exactly in the angle of the two moraines, but the narrowest point is 

 half a mile farther west. The crest of the Saginaw moraine from the 

 bend to Cass City is 80 to 100 feet or more above the channel floor, and 

 the channel runs close along its foot all the way. The inner angle of the 

 bend is held by a high, steep hill of drift with many boulders. It is the 

 northwest end of a lower ridge, which seems to belong to the eastern or 

 Huron lobe of the ice-sheet. This hill has been cut away to some extent 

 on its north and west sides, leaving many boulders tit its base. The base 

 of the moraine opposite is also quite steep, apparently from the same 

 cause. The hill in the angle evidently once extended a little farther to 

 the northwest. Southwest of Tyre morainic ridges mostly of moderate 

 height trend in a general east-and-west course. One of these lying next 

 south of the Tyre branch is high at its west end, like the one north of 

 Ubly, and appears at one time to have stood in much the same relation 

 to the river. It stands in the angle where the Tvre channel turns south- 

 west into the main channel. 



The Tyre branch was apparently opened before the Ubly, and the 

 former served as an outlet while the ice-front of the Huron lobe still 

 rested on the morainic ridge which now separates the two branches. A 

 later retreat of a mile or two by this lobe left an open space close along 

 the ice-front in the new position, and this became the Ubly branch. 

 After the Ubly branch opened the volume of discharge by the Tyre 

 channel must have been largely decreased, but the level of the lake was 

 probably not lowered much, for the heads of both branches are nearly 

 at the same level. Judging from the comparative magnitude of the 

 moraine between the channels and the later main moraine, it seems cer- 

 tain that the early activity of the Tyre channel must have been quite 

 short as compared with the later period of their combined activity. In 

 no other instance known to the writer is the relation of a great ice-dam 

 and the outlet of the waters which it retained so close or so clearty and 

 unmistakably shown. Ten miles north of Ubly the surface of the thumb 

 begins a gradual descent of 200 feet to lake Huron. The circumstances 

 in this case are such that there can be no possible doubt as to the place 

 of the ice-front while this outlet was active. It was not over a mile or 



