836 APPENDIX. 



would issue in the basin of the lake below low-water mark. 

 Digging for this mineral on the Chicago summit, promises indeed 

 not to be unsupported by sound hypothesis. 



After passing Chicago, of which a sketch is added, the sands 

 which begin to accumulate at the Konamik, the River du Chemin, 

 and the St. Joseph's River,* appear in still more prominent 

 ridges, skirting the eastern coasts to and beyond Grand River. 

 These sands, which are the accumulations of winds, are cast on 

 the arable land, much in the manner that has been noticed at the 

 Grand Sable on Lake Superior, and reach the character of strik- 

 ing dunes at the coast denominated the Sleeping Bear. The 

 winds which periodically set from the western shore, produce 

 continual abrasions of its softer materials, and are the sole cause 

 of these intrusive sand-hills. Pent up behind them, the water is 

 a cause of malaria to local districts of country, and many of the 

 small rivers upon this side are periodically choked with sand. The 

 sketch transmitted of this bleak dune-coast (omitted here), as it is 

 seen at the mouth of Maskigon Lake, will convey a false idea of 

 the value of this coast, even half a mile from the spot where the 

 surf beats. It is designed to show the air of aridity which the 

 mere coast line presents. The stratification regains its ordinary 

 level and appearance before reaching the Plate or Omicomico 

 River, and the peninsula of the Grand Traverse Bay, and the 

 settlements of the Ottawa Indians on Little Traverse Bay, afford 

 tracts of fertile lands. Point Wagonshonce consists of a stratum 

 of limestone of little elevation, which constitutes the southeast 

 cape of the strait. Here a lighthouse is needed to direct the 

 mariner. 



Lake Huron. — Notices of this sheet of water have been given 

 in our outward voyage. It appears rather as the junction of 

 separate lakes which have had their basins fretted into one another, 

 than as one original lake. Michigan is connected with it through 

 the Straits of Michilimackinac. The Georgian Bay, north of the 

 Manatouline chain, seems quite distinct. The Saganaw Bay is an 

 element of another kind. The Manitouline chain separates the 

 calcareous and granitic region, and its numerous trap and basaltic 

 islands towards the north shore, of which there are many thou- 



* The subjoined petrifaction of a leaf, apparently a species of betula, was ob- 

 tained on this river. See ante, p. 206. 



