262 Geology and Mineralogy of the 



ture is earthy-conchoidal. The only substance I met witii 

 in its fissures was brilliant and well-formed quartzose prisms 

 of a red colour. 



The north shore only of the upper basin exhibits any 

 stratification and it is of the transition quartz ; but whether 

 precisely of the same species as that of the rapid of the ba- 

 sins I know not. At Encampment Douce it changes ; in 

 becoming crystalline, compact, translucent at the edges, 

 conchoidal, and in passing occasionally by imperceptible 

 shades into a feldspathic form; the fracture being then foli- 

 ated, fragments schistose, lustre shining, and the translu- 

 cency at the edges very slight. It is very commonly stud- 

 ded with nodules of red and brown Jasper, averaging an 

 inch in diameter, and often arranging themselves in the 

 form of belts or stripes of from one to five feet in breadth, 

 mingled with round pebbles of white and black quartz. 

 Every part of the north west portion of Lake Huron abounds 

 in a conglomerate of this rock ; rich in Jaspers of all col- 

 ours, and occurring in blocks of great magnitude. I never 

 met with this species in situ. 



Small proportions of black and brown hoematite are not 

 unfrequent in the rock of Encampment Douce, and are as- 

 sociated with a bluish bla'ck, scaly, ore ; of iron I suppose. 

 Quartz is sometimes met with in a state of crystallization. 



I have not traced the transition farther than two miles up 

 the Great Nibish rapids. 



Having finished the observations on this class of rocks, 

 the following inferences may not be out of place. 



The " Serpent" rock was not deposited in the Wernerian 

 method of gradual deposition, but it is the product of the 

 forced union of two nascent formations ; and which it is 

 most easy to conceive took place horizontally, and not in 

 their present inclination : thereby pointing out an after-de- 

 pression or elevation. 



All this applies equally to the greenstone conglomerate : 

 of which it may be remarked that it is of a different era 

 from the " Serpent" rock, though composed of nearly the 

 same ingredients. The granitous compound is here in the 

 form of rolled balls ; which indicates that it had previously 

 existed independently, had been reduced to fragments and 

 subjected to attrition. 



