THE HAMILTON ASSOCIATION. 1 35 



NOTES ON THE NIAGARA FALLS ROCKS. 



Read before the Geological Section, June 26th, i8gi. 

 BY COL. C. C. GRANT. 



So much has already been written regarding the Falls of Niag- 

 ara that no point seems left for investigation. The rate of recession 

 has been determined by a host of writers, who widely differ on the 

 matter. I may add, however, that periodical surveys have been made 

 within the past fifty years, by which it is computed the gorge at the 

 present time recedes about 2.4 feet in the year. This recession must 

 have been much slower when harder material than the earthy shales 

 rested at the base. As the river gradually cuts back its way to 

 Lake Erie, owing to the dip of the beds, about twenty-five feet in a 

 mile, the Niagara limestones now at the top must occupy the lower 

 position of the softer layers, and then its backward course will be 

 considerably checked. 



While all I have stated is already known to the senior members 

 of the Geological Section, I feel assured they will pardon me for 

 explaining to our younger brothers of the hammer. The rocks 

 exposed in this neighborhood in descending order are as follows : 

 Boulder clay and gravel, containing fresh water shells have been 

 found resting on Niagara limestone, overlying shales and limestones 

 of the same series, followed by the Clinton beds, which are about 

 eighty-five feet in thickness and particularly well displayed along the 

 Niagara escarpment near Hamilton. This overlies the Medina beds, 

 shales capped by a freestone band, known as the grey band. All 

 except the first (Post-pliocene) contain corals, marine shells and en- 

 crinites, in addition to fucoids or sea plants. No reasonable doubt 

 can be entertained respecting the occurrence of the sea lilies in the 

 Medina sandstone. No crinoid, as far as I know^ has ever been 

 discovered here or elsewhere in these beds ; fragments of the 

 stalk of two distinct species were obtained, and both were in 

 better preservation than the Tentaculites (unrecorded) found at the 

 like horizon. I may notice here that in many instances these 

 marine remains have been mineralized or converted into iron pyrites. 



