[ells] notes on rock-contacts IN KINGSTON DISTRICT 99 



generally silicified and standing out of the sandy portion of the strata, 

 through the decomposition of the calcareous portion of the layers. 



In the lower part of the Ottawa river basin the regular succession of 

 formations continues upward till it includes the red Medina shales; but 

 ascending the river above Ottawa city the lower divisions gradually dis- 

 appear, and the rocks which rest upon the original floor are successively 

 higher in the scale, till on Lake Temiskaming these consist of the Upper 

 Silurian limestones. A similar condition of deposition is found along 

 the north side of the lower St. Lawrence. Thus, at the St. Maurice in 

 rear of the city of Three Elvers the Potsdam sandstone rests upon the 

 crystalline rocks, but farther east this sandstone disappears till in the 

 vicinity of the city of Quebec the Trenton limestone is the lowest for- 

 mation, the contact of this with the Archasan gneiss being well exposed 

 on the Ste. Anne river, a short distance above the Montmorency Falls. 



In the area south of the Kideau lake and thence to the St. Lawrence 

 at Brockville and for some miles east, the Palaeozoic formations are 

 practically confined to the two lowest divisions. On the iipper Rideau 

 lake, however, the succession upward again includes the Chazy shales 

 and limestone which cap the nighest part of the ridge south of that lake 

 in the township of Crosby, between Newboro and Westport. In this 

 area the overlying formations, if ever deposited, have all been denuded. 

 In the great area between the Ottawa and the St. Lawrence it is very 

 probable that several of these upper formations at one time existed, 

 since traces of several of them are still found at widely separated points 

 throughout this portion of the province. 



Along the St. Lawrence river, as far west as a point midway between 

 Gananoque and Kingston, the passage beds between the Potsdam and 

 Calcif erous can still be recognized ; but west of a line drawn from this 

 point to the upper end of the Eideau chain of lakes the Calciferous is 

 not seen with the single exception of the area in Crosby referred to. At 

 many places the only remaining deposit is the sandstone which is found 

 at intervals along the St. Lawrence to within a few miles of Kingston 

 and at a number of places along the line of the Eideau canal to the 

 height of land at Newboro on west Eideau lake. Where the Potsdam 

 sandstone is not developed in this area the lowest sediments consist of a 

 few feet or sometimes inches of a greenish marly shale or sometimes an 

 arkose which fills in the hollows of the underlying granite or gneiss. 



Frequently in this area the overlying rocks directly upon the sand- 

 stone are bluish limestones with shaly partings, which, in physical 

 characters, strongly resemble certain beds of Chazy age which occur in 

 the Ottawa basin. Where the sandstones are not deposited these lime- 

 stones rest directly upon the granite or other crystalline rocks of the old 



