OF THE HAMILTON ASSOCIATION. 



REMARKABLE LANDSLIDE NEAR 

 BRANTFORD, ONTARIO. 



*BY J. W. SPENCER, B. A. Sc; Ph. D., F. G. S. 



A gigantic landslide occurred on April 15th, 1884, at 6.45 p. m., 

 along the right bluff of the Grand River, two miles south south-east 

 ot Brantford. During the short period of three or four minutes, a 

 mass of quaternany deposits, measuring more than 300,000 cubic 

 yards were involved in the physical changes. 



In the vicinity of Brantford, the Grand River valley has a width 

 of about two miles, with the river meandering from one side to the 

 other, as its slope is there much less than above the city. Several 

 miles farther down, the valley becomes contracted again. It is 

 bounded by bluffs rising about 80 feet above the flood plains, with 

 the river flowing ten or more feet below their level. 



The lower and principal portion of the bluffs, at the landslide, is 

 composed of Erie clay, while the upper beds are made up of the more 

 sandy Saugeen clay of Canadian geologists. The underlying rocks 

 belong to the higher series of the upper Silurian system, but these 

 are exposed on the banks of the river, only above and below this 

 wide alluvial plain, along which our landslide occurred. The struc- 

 ture of the Erie clay, as shown in the landslide, is much more dis- 

 tinct than is usually seen in the older exposures, where the vertical 

 or oblique joints have been observed by weathering. The formation 

 consists of a very hard drab (blue when wet"* clay splitting into regu- 

 lar and thin slabs. The jointed structure is less apparent in the 

 vertical walls, left standing, than in the fallen masses, where it is 

 broken into pyramids, from a few feet to more than ten in height. 

 It was from the shpping along these planes, and those of the natural 

 bedding that the slide was produced. 



The geological interest attached here is, that we can see : (i) 

 The character of a slide which has not resulted from undermining 

 action, but from hydrostatic pressure, in the ever opening joints, 

 where the clay is constantly becoming softened. (2) The dynamical 

 effect upon laterally confined plastic clay, below the horizon, to which 

 the fallen masses could reach; and (3), the manner in which the 



* Professional geology, University of Missouri. 



