142 ROYAL SOCIETY OF CANADA 



The second t'ormatioii. viz.,the Chaz}-, is separal)le into two portions, 

 the lower of wliieh is a shaly and sandy series, while the upper is largely 

 calcareous. East of Ottawa, the lowest members can be Avell studied along 

 the Gren ville and Carillon Canal, while the upper portion is well developed 

 in the area to the south. Excellent sections are also exposed in the vicinity 

 of OttaAva city and along the shores of the Ottawa River at Aylmer, and 

 on the southern bank in the townships of March and Fitzi-oy. 



The lowest beds of the Chaz}- at these places consist of a somewhat 

 coarse greenish-gray grit or sandstone in places conglomeratic in char- 

 acter, and in general aspect not unlike some of the gritty beds of the 

 Sillerv formation. The.se have a thickness of only a few feet and they 

 graduate upwards into finer arenaceous beds of a light greenish-gray 

 shade, with a considei'able thickness of shales. Certain bands in this 

 ])ortion contain fossils and are fucoidal. Intercalated beds of limestone 

 ai»pear in the upper part, which gradually becomes more calcareous till 

 the formation is essentially a limestone. At Aylmer the thickness of the 

 lower portions of the Chazy, to the base of the limestones proper, is 

 apparently not far from one hundred to one hundred and twenty feet. 



The thickness of the upper or calcareous portion varies greatly at 

 different places, ranging from fifty to nearly one hundred feet. In its 

 upper part the limestones become nodular, and certain beds of grayish 

 colour are largely composed oî Rhynconella plena.. 



The passage from the upper beds of the Chazy to the overlying beds 

 of the Bird's Eye and Black Elver, which lie between those just described 

 and the main mass of the Trenton formation, appears to be gradual and 

 to present no well defined break in the succession of the strata. The 

 Black River, which in Canada includes the Bird's Eye in its lower portion, 

 consists of certain dark brown and black limestones often cherty, break- 

 ing with a marked conchoidal fracture, and distinguished largely by the 

 presence of Tetradium fibratum, Avhich is in ]jlaces so abundant as to con- 

 stitute almost the entire mass of some of the beds. Certain other fossil 

 forms, such as Columnarid Halll and Orthoceras Biyshiji are particular!}'" 

 developed in the strata of this formation but from the difficult}^ of clearly 

 distinguishing these limestones as a grou]) from the Trenton at many 

 l)laces, tlie}' are now generally included in the latter formation. The 

 thickness of the Bird's Eye and Black River is given in the Geology of 

 Canada^ as only thirtj'-eight feet for the area in the lower Ottawa basin, 

 near Montreal, l)Ut on the upper Ottawa, as at Eganville, Douglas, etc., 

 this is increased to over one hundred feet. 



The Trenton is essentially a limestone formation throughout. The 

 lower portion consists largely of grayish and l)lack, often bituminous 

 beds, holding an abundance of fossils, among which Stenopora fibrosa is- 

 very abundant ; the upper 350 to 400 feet are for the most part dark 



' Geology of Canada, 1863, p. 137. 



