*/V. W. Portion of Lake Huron. 263 



it may be conjectured that these two rocks owe their ori- 

 gin to the trap and granite on the north east, or that they 

 have been evolved from the same repository but in closer 

 combination. 



The Huttonian theory explains these phenomena, by pro- 

 viding powers and materials. , 



Further evidences of the convulsions to which this part 

 of Lake Huron has been submitted, are afforded by the six 

 distinct species of conglomerate in the state of debris, and 

 as many of breccia which every where abound ;* and by the 

 brecciated and vesicular limestones of Michilimackinac. 



Most probably the first flsetz sandstone is the rock in jux- 

 ta position on the north west, with the transition quartz 

 just described. 



It have not visited in favorable circumstances the line of 

 junction, and I saw the former first distinctly at the falls of St. 

 Mary, among the petty rapids of the marshy islets around 

 the falls. In the summer of 1819, while travelling in a ca- 

 noe, at dusk, I observed in Lake George not long after leav- 

 ing the inclined strata, a number of islands with moderately 

 high cliffs of horizontal rock, breaking into parallelopipeds, 

 which perhaps are the first flaetz sandstone, especially as 

 much of its debris is found with sha7-p edges on the rapids of 

 the Great Nibish. 



The portage of the falls of St. Mary furnishes the best 

 means of examining the stratification of this mineral. The 

 stores of the North West Company are founded upon itj 

 and it is traced, imperfectly covered with mould and herb- 

 age to the insular channels of the falls, in horizontal or 

 slightly inclined layers of some thickness. It breaks and 

 splits readily. It is soft. Its colours are principally browis 

 and dull white or red, occasionally with yellow spots or cir- 

 clets. It is the sandstone of the Genesee country N. Y 

 without so large an impregnation of iron. 



This rock is every where surrounded by morasses. 



In returning through Lake George into Lake Huron by ei- 

 ther side of Isle a la Crosse, we gradually emerge from swam- 

 py musquito grounds into a calcareous formation, as is seen 

 by the debris on the beaches. No fixed stratum, I believe, 

 i- met Vv^ith but on the North side of St. Joseph, or in the 



* These are classed in the Appendix 



