CHAPTER VIII. 



WAVERLY GROUP. 



The light-colored, greenish, arenaceous shales, on top of the 

 black shale exposed along the shore of Big Traverse Bay, may 

 possibly be an equivalent of the Erie shales of the Ohio geologists, 

 but no fossils have been found by which this question can be 

 determined, and no outcrops of equivalent beds are seen in 

 any other part of the State. The shales in the southern part of 

 the peninsula, which were considered by Winchell as a part of his 

 Huron shales, occupy a higher position, and must be identified 

 with the Waverly group. 



The Waverly group is the most important rock series on the 

 lower peninsula — not only because it forms the surface rock over 

 the greatest part of it, but for its economical value. It is the re- 

 pository of the Michigan salt brine, and furnishes almost the only 

 good building-stone we have on the peninsula. The Huron grind- 

 stones, famous for their excellence, are likewise taken from this 

 group. The Michigan salt group of Prof. Winchell is a series of 

 rock beds above the Waverly group, which I shall consider in 

 connection with the subcarboniferous limestones ; they contain 

 large quantities of gypsum, but no salt brines of practical value. 



The Waverly group forms, underneath the drift, the surface 

 rock over half the extent of the peninsula, but its natural out- 

 crops are very limited, either horizontally or vertically. The 

 upper division of the group is much better exposed than the 

 lower, which in part is only known through the results of deep 

 borings, information of a very unsatisfactory kind. The vicinity of 

 Port Austin and the shore belt east and west from it offer a very 

 good field for the study of the upper part. 



From the west end of the village, to Flat Rock Point, the shore is 

 nearly all the way lined by low cliffs of a coarse-grained, soft, 

 whitish sand rock, in thick, massive beds. The cliffs have an ele- 

 vation of from 8 to lo feet above the water-level, and on the rising 

 ground back from the shore, additional ledges of a similar sand 



