ON LANDSLIPS. 321 



height above the valley of some 3,000 feet ; and as the 

 distance is about 8,000 feet, the slip gradient would be fully 

 1 in 3. 



When I visited the place in 1857, I was greatly struck by 

 the enormous heap of rocks and rubbish lying in the valley 

 below. The masses of rock, many as big as a cottage, were 

 thrown into all sorts of fantastic attitudes, and thS" force 

 and velocity which the mass had acquired was evidenced by 

 the slip rubbish having travelled quite across the valley, a 

 mile and a half wide, and some distance up the opposite 

 slope, some very large blocks having gone a good many feet 

 up the steep slope of the opposite mountain. The debris, 

 which covered more than a mile in width of the valley, lay, 

 it was said, 100 feet deep above it and the buried houses, and 

 had filled up one end of a small lake named the Schwanau 

 See. It was a scene of marvellous devastation when I saw it. 

 After scrambling some -way up the slip, the cause of it 

 was obvious. The dip of the strata was about parallel with 

 the general slope of the mountain, something like 3 to 1 — 

 quite a climb, in fact. The slipping surface was formed by 

 a bed of pale-coloured clay, having a stream of water over 

 it. Standing on this bed of clay and looking round, there 

 were the walls of the slip quite 300 feet high, it seemed to 

 me, and vertical. It looked as if there had been two nearly 

 parallel vertical fissures through the rock, passing right up 

 the mountain slope, perhaps 400 yards apart where I stood ; 

 and that this mass of rock had suddenly lost its hold upon 

 the two sides and slid down, upon this bed of moistened 

 clay, for the whole height of the mountain side, thundering 

 into the ill-fated valley below like the shock of an earth- 

 quake. The walls of rock were composed of strong beds 

 of great thickness, thirty or forty feet it appeared to me and 

 as was fully borne out by the great size of the broken blocks 



