422 THE CANADIAN NATURALIST. [Dec 



Lake Cliamplain, where it was first described by the New York 

 geologists. In Canada it is associated with sandstones and shale. 

 and is here described as Chazy formation. It is exposed in the 

 cutting of the Grenville canal, and there crosses the Ottawa to 

 Hawkesbury. In its geographical distribution, it forms a zone 

 around the geological depression between the Ottawa and the St. 

 Lawrence. It forms two patches on the calciferous outlier of the 

 Lac des Chats, also of the lowest outlier of the Alumette Islands. 

 The arenaceous part of the Chazy is seen at Aylmer, in Hull, and 

 in the eleventh range of Eardley, on the north side of the Ottawa. 

 It is also found in the Townships of Huntly and Ramsay. The 

 great mass of limestone which overlies the Chazy formation is 

 divided into three portion^ by the New York geologists. The 

 divisions are supposed to have been characterised by peculiar fossils. 

 However, in Canada, a separation of this kind cannot be definitely 

 carried out, owing to the circumstance that the Birdseye and 

 Black River formations become very indistinct ; they are, in con- 

 sequence, grouped together. Not only are the strata blended to- 

 gether, but also the fossils characteristic of the one are found in 

 the other ; thus the difficulty of division. According to Sir Wo 

 Logan, the Birdseye, Black River, and Trenton formations con- 

 stitute one of the most persistent and conspicuously marked series 

 of the strata of the Lower Silurian period of North America. 



The limestone of the Trenton group is found extensively in 

 Canada East and West, and particularly between the Ottawa and 

 the St. Lawrence, but more especially around the capital of 

 Canada, — Ottawa. The limestones of this locality are affected by 

 two parallel dislocations between five hundred and six hundred 

 yards apart, west of the Rideau. "One of these dislocations comes 

 to the Ottawa a little below the exit of the canal, in a small up- 

 throw to the south ; and the other about six hundred yards above it,, 

 beyond the Barrack Hill, is a downthrow of seventy feet in the 

 same direction." Farther west this series of limestones come up 

 against the Gloucester and Hull fault, extending from the west 

 side of the junction gore of Gloucester across the Ottawa to the 

 front of the sixth lot of the fifth range of Hull. Owing to these 

 various faults it has been found difficult for the Geological Survey 

 to estimate the thickness of the series in this neighborhood. It is, 

 however, computed that the total volume of the limestones of this 

 locality will not fall short of six hundred feet. 



Utica Slate (so termed from Utica in the State of New 

 York). — It comprises a series of dark-brown, bituminous shales,. 



