LANDSLIP IN POKTNEUF COUNTY, QUEBEC 485 



slip took place on the east side of the river, at a distance of 3 miles from the vil- 

 lage of Saint Casimir. The results were disastrous to the farmers whose property 

 was affected, one life was lost, two inhabited houses, a school-house, two barns, 

 and several outbuildings were destroyed or engulfed, and cattle, horses, and other 

 live stock perished. 



Examination made 



On May 29 I visited and examined the locality, taking some photographs of the 

 scene, and a few days later, at my request, Mr E. Chalmers, of the Geological Sur- 

 vey, accompanied by Mr J. Keele, made a closer study of the circumstances as 

 well as an approximate survey of the place, and procured additional photographs. 

 The following brief description is based partly on my own observations, in part 

 on those of Mr Chalmers, and is intended merely to outline the chief facts of in- 

 terest, from a geological standpoint, respecting a mode of denudation that appears 

 to have been not uncommon in the clay-floored plain of some parts of the Saint 

 Lawrence valley. 



Character of the Country 



At the place in question, the Riviere Blanche, a small stream, occupies a valley 

 running from north to south, about 1,000 feet wide, between sloping banks, 25 to 

 3o feet high, and nearly uniform in this respect. The surface of the country in 

 the vicinity is for the most part under" tillage, and is practically level to the eye, 

 being a terrace-flat or plain composed of the marine Pleistocene deposit known as 

 Leda clay, the whole thickness of which is not here anywhere shown. The clay 

 is occasionally covered by arenaceous deposits a few feet thick and referable to the 

 Saxicava sands. 



To the north of and adjoining the wide crater-like depression produced by the 

 landslip here particularly described there is, however, an irregular depressed 

 area of nearly the same size, now under tillage, that evidently represents the site 

 of a much earlier sli]) of the same character. Still farther to the north, and at a 

 distance of 50 chains from the recent slip, the road, which runs parallel to the river 

 valley and near it, crosses a low ridge of boulder clay. This material may be pre- 

 sumed to underlie the Leda clay elsewhere, but the subjacent rock is nowhere seen 

 in the vicinity. 



Mode and Extent of the Movement 



A small runnel of water appears to have entered the Blanche valley at the point 

 where the material of the landslip subsequently found issue, and I was informed 

 that previous to the main slip a small slide had been noted to occur at this spot. 

 At half past five in the morning the inhabitants were alarmed by the movement 

 of the soil, which then suddenly began and continued for three or four hours. The 

 immediate bank of the river valley appears in the first place to have given way 

 along a front of about 200 feet in width, and the gap thus made rapidly extended 

 inland, forming an opening through which a great body of clay behind rushed 

 tnmultuously out into the Blanche valley. At a short distance from the bank of 

 the valley the width of the area affected greatly enlarged, the sides of the de])res- 

 sion collapsing and falling into the gulf, until a crater-like hollow of bottle-shaped 

 outline and opening on the valley by a narrow neck was produced. 



