200 Sir W, E. Logan on the Quebec Group j Sfc, 



Orleans. The road from Beauportto tlie Montmorency runs over 

 a floor of Trenton limestone, which has a very small dip towards 

 the St. Lawrence ; farther back from the river the rock has a 

 gentle dip in an opposite direction giving evidence of a very flat 

 anticlinal form, which could scarcely be detected without the aid 

 of the general distribution of the formations in the neighbourhood. 

 On the south side of the road there occurs a dislocation which 

 can be traced the whole way from Beauport church to Mont- 

 morency falls, where the effect it produces is easily discernible. 

 Here the channel of the Montmorency is cut down through the 

 black beds of the Trenton formation to the Laurentian gneiss on 

 which they rest, and the water at and below the bridge flows down 

 and across the gneiss, and leaps at one bound to the foot of the 

 precipice, which immediately behind the water is composed of 

 this rock. At the summit the Trenton beds are seen on each 

 side ; on the right bank they have a thickness of about fifty feet, 

 and are marked by the occurrence of Leptcena sericea (Sowerby), 

 Strophomena alternata (Conard), Orthis testudinaria (Dalman) 

 Lingula crassa (Hall), Conularia Trentonensis (Hall), Calymme 

 BlumenhacMi (Brongniart), and Trinudeus concentricus (Eaton). 

 The dip of these beds is down the stream at a very small angle ; 

 but at the foot of the precipice and immediately in contact with the 

 gneiss, about the same thickness of black limestone is tilted up to 

 an angle of fifty-seven degrees ; it is followed by about an equal 

 amount of black bituminous shale with the same slope. In this 

 attitude these rocks climb up the face of the precipice present- 

 ing their edges to the chasm on each side ; they are succeeded by 

 about eight feet of hard grey sandstone weathering brown in beds 

 of from ten to eighteen inches, interstratified with black shale ; 

 on this repose gray arenaceo-argillaceous shales composing the 

 sides of the chasm out to the waters of the St. Lawrence, the dis- 

 tance being about a quarter of a mile, and the dip which is 

 towards the St. Lawrence by degrees diminishing to about thirty- 

 five degrees. 



These tilted beds are fossiliferous, the species contained in the 

 limestones being Stenopora petropolitana (Pander), Ptilodictya 

 acuta, (Hall), Strophomena alternata, Leptcena sericea, Orthis 

 testudinaria, Camerella nucleus (Hall), Lingula allied to L. 

 ohtusa, Descina crassa (Hall), Bellerophon hilohatus (Sowerby), 

 Conularia Trentonensis, an undetermined Orthoceras, Cyrtoceras 

 (Mnstrictum (Hall), Calymme Blumenbachii, Cheirurus pleurexan- 



