«8 ROYAL SOCIETY OF CANADA 



between the crystalline series of the Ottawa and that of the Kingston- 

 Brockville area, which is now occupied by these newer sediments. 



While there are many interesting contacts visible at different places 

 as the result of the intrusive nature of the granites through the other 

 crystalline rocks of the Grenville and Hastings «eries these have been so 

 frequently referred to in various papers and reports that they need not 

 here be further considered. The same remark also applies to the peculiar 

 faulted contacts east of the St. Lawrence, which occur in connection with 

 the great Champlain fault. The object of the present paper is to 

 describe some of the contact phenomena which are visible in connection 

 with the deposition of the Palaeozoic sediments upon the eroded surfaces 

 of the crystalline rocks of the Kingston district. 



In the portion of the province of Quebec, west of the Champlain 

 fault, as well as in eastern Ontario, the Potsdam sandstone forms the 

 lowest division of the Palaeozoic series and is regarded by Canadian 

 geologists as representing the base of the Cambro-Silurian or Ordovician 

 system. Its thickness in Canada is nowhere great, rarely reaching 100 

 feet, except in the area adjacent to New York state east of the St. Law- 

 rence, the thickness of the formation evidently increasing in that direc- 

 tion, but south of the Canada line it develops rapidly and has a thick- 

 ness of some hundreds of feet. It is here, by the United States geolo- 

 gists, regarded as forming the upper member of" the Cambrian system 

 from the presence of Cambrian fossils in the lower portion of the forma- 

 tion, though the transition beds into the overlying Calciferous are the 

 same on both sides of the St. Lawrence. 



In many places throughout the Eideau-Kingston district the basal 

 beds of the Potsdam formation consist of a coarse conglomerate which 

 is made up of pebbles of the old crystalline rocks, sometimes of large 

 size, and well rounded, embedded in a sandy but sometimes calcareous 

 paste, the latter being usually found when the conglomerate rests upon 

 the crystalline limestone as is occasionally the case along the Kideau 

 lake, where this basal conglomerate is in places well displayed. 



This conglomerate passes upward into more regular sandy beds in 

 which there are occasional layers also containing pebbles which, how- 

 ever, consist for the most part of white quartzite, and these sandstones 

 graduate upward without break into strata which become calcareous till 

 the rock finally passes into a dolomitic limestone which constitutes the 

 Calciferous formation. 



Between the sandstone proper and the dolomite there are certain 

 layers known as the transition beds which range in thickness from five 

 to forty feet, and these are often highly fossiliferous, the fossils being 



