OF CENTRAL CANADA PART V. 349 



the greater part of their course they are more or less intimately asso- 

 ciated in complicated stratigraphic relations, with the Lower Silurian 

 Utica shales, the latter appearing in many places to dip under them. 

 They are distinguished however from these Utica beds by their pecu- 

 liar graptolites. In Brome and Shefford the formation is broken 

 through by trachytic mountain-masses which cover areas of many 

 square miles in extent (see below). These trachytic areas lie between 

 the central crystalline range and the great Champlain fault, and they 

 belong to the same eruptive series as the trachytic and trappean 

 masses of the upper St. Lawrence District, described on a preceding 

 page. The formation appears also along the southern edge of the 

 crystalline country west of Kamouraska in contact with altered 

 Upper Silurian strata, as seen about St. Joseph on the Chaudiere and 

 in the townships of Wolfestowu, Ham, Richmond and Sherbrook. 



The Lower Silurian formations within the Appalachian District 

 lie on the western and northern limit of the Calciferous (Quebec) 

 series, and in many places are mixed up with these latter in complicated 

 relations. They consist mostly of Hudson River and Utica strata, 

 but some Trenton (and perhaps Chazy 1) beds have been recognized 

 in Missisquoi, at the extreme south-western limit of the district, and 

 the steeply-dipping black slates which occur on the St. Lawrence 

 near Point Levis, and which were originally thought to occupy a 

 geological position below the Potsdam horizon, may belong to the 

 same formation, if not to the succeeding Utica and Hudson River 

 series. Representatives of these latter consisting mostly of grey and 

 black slates and greyish sandstones, whilst the associated Calciferous 

 (Quebec) beds are chiefly in the form of red and greenish, or more 

 rarely black, shales, with limestone conglomerates, yellowish dolo- 

 mites, and greenish-grey sandstones occur largely along the coast as 

 far east as the Magdalen River ; and beyond that point, they occupy 

 the entire-coast line to Cape Rosier, in the form of disturbed and 

 strikingly contorted strata. At the Magdalen and elsewhere, accord- 

 ing to Mr. R. W. Ells (Geological Survey Report 1882), the Utica 

 beds appear to underlie the older Calciferous formations. No certain 

 evidence has been obtained of the occurence of Lower Silurian strata 

 in that portion of the District which lies south of the central crystal- 

 line range of country, all the strata being there regarded as of Upper 

 Silurian and Devonian age \ but some of the argillaceous slates which 

 occur there may perhaps be Lower Silurian. 



