12 LOWER PENINSULA. 



water. The coarse boulder drift all through the southern part of 

 the peninsula appears not to occupy the lowest position, in 

 which most frequently a hard, dark blue, sandy clay, with 

 pebbles and some boulders intermingled, is found in layers 

 of considerable thickness. It is known among laborers by the 

 popular name of Jiard-paii. The beds of clay, sand, and gravel 

 in the stratified drift arc not deposited in a certain order of 

 sequence which would hold good even for limited precincts ; every 

 locality has to be studied for itself, and if denudations of larger 

 horizontal extent are observed — which opportunity sometimes 

 happens in the bluffs of the lake shores — we see constant local 

 changes in the details of structure, although in some principal 

 features a uniformity of the strata may be perceptible. This irreg- 

 ularity in the structure of the stratified drift explains itself, if we 

 consider the conditions under which the deposits were formed and 

 that the already formed deposits were by subsequent causes re- 

 peatedly displaced. During the slow emergence of the peninsula 

 from the w^aters, much of the surface material was shifted about 

 by waves and fluctuations of the retiring lake, and when the river 

 channels began to form, and deep valleys were carved in all direc- 

 tions through the drift masses, immense quantities of material 

 became displaced and deposited anew in a different order, governed 

 entirely by local circumstances ; and this process of destruction 

 and building up is to this day in constant operation. 



In the report on the Upper Peninsula, I have described, among 

 the drift materials, an impalpably fine red-colored clay deposit of 

 considerable thickness, which rests there frequently in immediate 

 superposition on the older rock beds, and is in some localities — as, 

 for instance, at Au Sable Point, on Lake Superior — overlaid by 300 

 feet of sand and gravel beds of the drift. In the drift deposits of 

 the Lower Peninsula a similar well-stratified red clay is observed,' 

 but there it is not found at the base of the drift. It has a higher 

 position, and is underlaid by stratified sand and gravel beds, while 

 below them follows the non-stratified tough blue clay with pebbles, 

 which, in the southern part of the State, is always the lowest 

 of the drift. The relative position of this red clay to the other 

 drift beds is best seen in the high bluffs lining the shore in the 

 northwest part of the peninsula. The lowest blue gravelly clays, 

 in non-stratified condition, are sometimes visible at the base of the 



