﻿224 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 9, 



The south side of Lake Huron, in the State of Michigan, abounds 

 in sand-banks and low ledges of horizontal limestone ; the interior 

 being low and undulating, with ridges of sand and loamy hollows, in- 

 terspersed with small lakes : the region is very fertile in parts. 



The detritus of Lake Huron, like that of Lake Superior, is accumu- 

 lated principally on its eastern and southern coasts. But here the 

 erratic boulders are everywhere seen ; and they abound in immease 

 numbers on the north shore ; on this latter portion of the lake's 

 margin I did not see a single ancient terrace, which nevertheless may 

 exist. The boulders occupy the hill-sides, beaches, and shallows of 

 main and island ; they are little worn, of the usual large size, and lie 

 irregularly on the surface. Their numbers are great on the most 

 western Manitouline, Drummond Isle, and considerable on the Little 

 Manitou. 



Blockhouse Hill, once the west end of Drummond Isle, is the 

 level summit of a slope 400 yards inland, behind Collier's Harbour 

 Village. Eighty or a hundred feet above the lake, just where the 

 slope rises into a perpendicular ledge of limestone, it is strewn with 

 large primitive boulders, but little rolled ; and the village street is 

 rendered almost impassable by blocks from 4 to 10 feet long, although 

 many have been removed. They are principally local, but among 

 them we see much syenite, trap, quartz-rock, and some jasper- 

 pudding-stone ; — all from the N. and N.N.E. 



The higher grounds of the contiguous Manitouline, about the 

 middle of its northern side, are rugged with these same primitive 

 erratics. 



On the sides of the steep slope forming the south point of St. Jo- 

 seph Island, there are the remains of successive belts of water-worn 

 erratics of large size, one above another, with a few yards' interval 

 between each. Besides these, many blocks are scattered about in the 

 vicinity. The same occurs eight miles to the east, in Worsley Bay, 

 near the south-east point of the island. 



Between St. Joseph and the False Detour, and perhaps four miles 

 from the latter, is an island called in the map of the American Boun- 

 dary Commission, High Cliff Island, one of a group. On the summit 

 of this cliff (which is 100 feet high, and consists of fine granular 

 sandstone), Col. Delafield informs me there is a range of water-worn 

 stones, mostly limestones, traps, and quartz-rock, regularly strewn, 

 as on a beach, for 200 feet in length. 



These instances of the remains of ancient deposits might be greatly 

 multiplied, as they are very usual in this lake, when the vegetation 

 permits them to be seen. The debris crowning the heights, or hang- 

 ing on the slopes, of this part of Lake Huron, is almost altogether 

 gneiss, syenite, and trap ; derived not from the S., but from the N. 

 and N.N.E. ; for no such rocks exist in a southerly direction for 

 2000 miles, if we except the Alleghanies, which are themselves very 

 remote. I cannot distinguish this debris from the fixed rocks on the 

 north of Lake Huron, and towards and in Lake Nipissing. 



The high cliffs of the main in the narrows of Pelletau are of coarse 

 greenstone-slate and greenstone-conglomerate ; but the surface is so 



