310 APPENDIX. 



whicli is a translation of the Roche Blanche of the older voyageurs. 

 The Detroit claj-formation still characterizes the coast. 



First Emergence of Eock, m place, above the Surface. — 

 AVe are passing, in this section, along and near to the outcrop of 

 the secondary strata of the peninsula, but these strata are covered 

 with a heavy deposit of diluvial clays, sands, and pebble drift. 

 The first emergence of fixed rocks, above the line of the drift, 

 occurs after passing Elm Creek in the advance to Ship Point 

 [Poirde aux Barques). It is a species of coarse gray, loosely com- 

 pacted sandstone, in horizontal layers. This rock continues to 

 characterize the coast to and around the Ship Point promontory 

 into Saganaw Bay. It possesses a few fossil remains of corallines; 

 but the rock is not of sufficient compactness and durability for 

 architectural purposes. It is conjectured to be one of the out- 

 lying series of the coal measures, of which this coast exhibits, 

 further on, other evidences. 



Saganaw Bay, — The phenomena of this large body of water, 

 which is some sixty miles long, appear to indicate an original 

 rent in the stratification, having its centre of action very deep. 

 If the peninsula of Michigan be likened to a huge fish's head, 

 this bay may be considered as its open mouth. We crossed the 

 inner bay from Point aux Chenes, where it is estimated to be 

 twenty miles across.'^ The traverse is broken by an island, to 

 which the Indians, with us, applied the name of Sha-wan-gunk.f 

 It is composed of a dark-colored limestone, of dull and earthy 

 fracture and compact structure. It presents broken and de- 

 nuded edges at the water level. I observed in it nodular masses 

 of chalcedony and calc. spar. The margin of the island bears 

 fragments of the boulder stratum. 



Highlands of Sauble. — On crossing the bay, these highlands 

 present themselves to view in the distance. They are the north- 

 eastern verge of the most elevated central strata of the peninsula. 

 Their structure can only be inferred from the formations along 



* Ships make the traverse where it is sixty miles wide. 



f The reason of this name I did not learn. It is apparently the same name aa 

 that bestowed on a mountain range in Orange and Ulster Counties, New York, 

 lying south of the Catskills, where it is sometimes called, for short, Shongum. 

 The meaning is, evidently, something like South-land-place. The local unk may 

 be translated hill, island, continent, &c. &.c. 



