162 Rev. A. Irving— Bergstiirse,” or “ Landslips:” 
those of Hottingerberg in 1878 (resulting from an unusually wet 
spring and early summer); between 80 and 40 (on a small scale) 
between Utznach and Weesen in the year 1846; Bdéttstein in Canton 
Aargau in 1876; one on the Zirichberg above Oberstrass in 1770; 
one above Weggis on the slopes of the Rigi in 1795 (lasting 14 
days); also a larger one which in 1797 buried 37 houses with many 
gardens and other property of the village of Brienz, and befouled 
the waters of the lake for several months. 
2. Schutistiirze.—It sometimes happens, especially in cases where 
strata of various composition dip into the mountain, that minor 
lateral valleys are formed on the high alp; and in these a quantity 
of débris is sometimes accumulated. As the strata which inclose 
such an accumulation of débris get further worn away by weather- 
ing, a passage is opened for the rubbly mass to find its way down 
into the valley below; and this it usually does, when, as the result 
of a more than usually wet season, or of the descent upon it and 
subsequent thawing of avalanches, it gets saturated with water. 
One of the most remarkable examples of these Schuttstiirze hap- 
pened in 1868 in the spring of the year, at Bilten in Canton Glarus. 
Above the village rises the Hirzliberg, composed of the conglomerates 
commonly known to Swiss geologists as ‘ Nagelfluh,’ sandstones and 
marls. Upon the brow of this mountain a minor valley 300 metres 
long, 50 broad, and 15 to 20 deep, was formed and filled with the 
loose detritus produced by the weathering of the rocks above it. 
The valley lies about 450 métres above the village of Bilten. An 
avalanche descended upon it during the previous winter, and in 
melting saturated the loose mass. As the result of this the mass 
descended in a ‘dirty thundering waterfall’ of mud and stones 
through an opening in the front ridge of the mountain, continuing 
for some 48 hours. The dimensions of the mass which descended 
were estimated at 180,000 cubic métres. 
Another instance occurred on a smaller scale at Oberarth on the 
side of the Rossberg in 1874; and in the summer of 1881 an 
enormous mass descended in a similar way in the Hisak Thal, by 
which the channel of that rapid river was temporarily blocked up. 
This was the result of a sudden and heavy rainfall; and when I 
saw it about a fortnight later, the houses of the lower part of Sterz- 
ing were still standing in the water, which had flooded that part of 
the valley owing to the obstruction mentioned. 
In the two varieties of Bergstiirze which follow, a portion of the 
actual strata of the mountain, and not a mere accumulation of loose 
materials on the mountain-slope, makes its descent into the valley 
below. 
3. Felsschlipfe.—The typical ‘ Felsschlipf’ results from the loosen- 
ing of the upper strata, where the general dip is towards the valley, 
the antecedent conditions being prepared for it by the erosion of the 
sides of the valley. The lower part of the mountain is often worn 
in this way into a slope much steeper than the dip-slope of the 
strata in the mountain above. The occurrence of soft clayey strata 
between the more massive beds is of course favourable to the pro- 
