^264 Geology and Mineralogy of the 



latitude of the Manitoulines. With the exception of the 

 narrow selvage of transition and primitive on the North main- 

 land, the whole of Lake Huron rests on secondary lime- 

 stone. I have myself noticed it encroaching on those class- 

 es as far East as the river des Francois on the North shore 

 • — and found it to be the only living rock in the South and in 

 the Manitouline chain of Islands ; including that of St. Joseph. 

 The calcareous basin of Lake Huron (and the remark 

 jiiay be extended to Lower and Upper Canada) differs from 

 those of Europe* in essential particulars: in being oftefi 

 non-crystalline and full of organic remains while in cofftact 

 with the oldest rocks — without observing their direction and 

 inclination. Again in the Canadas, limestones deposited in 

 the midst of flaetz countries are sometimes highly crystalline 

 and crowded with fossilized animals. 



The following facts illustrate these observations. 

 Between the mouth of the River Des Francois and the 

 groupe of islands named La Cloche, there are several isle& 

 of some magnitude whose centre or nucleus is of gneiss, lof- 

 ty and barren — girded by a broad zone of dark coloured 

 horizontal limestone which is loaded with vegetation. I 

 landed on one of them and found the rock to be soft and 

 knotty, and full of organic remains. The same appearance 

 occurs between La Cloche and Messassaga. 



A gentleman of the party met with an island oft' the River 

 Thessalon composed of a number of parallel ridges of gran- 

 ite much disturbed and broken; whose intervals contain 

 horizontal limestone thus. [See the Plate, fig. 2.] 



In the rear of the promontory of the Cedar Island, passage 

 near Kingston, on Lake Ontario, I observed horizontal 

 compact, dull, brown limestone overlying gneiss in a simi- 

 lar manner. Farther east, in the contracting portion of Lake 

 Ontario, this Rock forms the immediate bank with the 

 primitive emerging behind it thus. [See the Plate fig. 3.] 

 The intervals of these mounds are often (as in Lake Hu- 

 ron) filled with secondary limestone. 



An occurrence nearly the same takes place at the Falls 

 of Montmorenci near Quebec. 



Repeated instances are met with in the thousand islands 

 near Kingston where white quartzy sandstone, rests, in hor- 

 izontal layers on granite. 



* lilnrope. howpvpr. rlo°« rontnin ri few similar examples. 



