be tee Senet Ro 
§16 
furrowed from the top to the base; and 
seem to testify that Ruifiberg, in different 
epochs, and on different parts of its sur- 
face, has suffered dissolutions similar to 
that which has lately happened. 
The summit* of the mountain has not 
fallen: it presents a_ horizontal line, 
which unites two inclined planes, cover- 
ed with grass; one plane directs itself. 
towards a poimt intermediate to the 
Jakes of Zug and Egeri, and the other de- 
scends towards the lake Lowertz. It 
was upon tlus last surface, and about a 
toise below the summit, that the separa- 
tion began to be felt. The direction it 
pursued was, before this catastrophe, 
shightly cut like a gutter, or little valley, 
rather deep towards the bottom of the 
mountain, but losing its cavity near the 
summit. Along this way, throughout the 
meadows and wood, were to be seen 
blocks of blend here and there, half bu- 
ried. 
The east side of the driven cliff towards 
Schwitz, evidently shews that in the tract 
made by the separated section, the 
higher layers sunk vertically on the lower 
ones, by reason of a void space formed 
between them, in a direction parallel to 
their planes, and to the slope of the 
mountain, 
This side presents a cut, or. vertical 
wall, which was not seen previously to 
the drifting: the height of the wall, above 
the upper surface of the drifted and 
fallen section, shews the thickness of the 
pressing layery at the summit of Ruffi- 
berg. This cut is about fourteen feet 
high, near the top of the mountain; but 
it jnereased insensibly, and at some dis- 
tance lower it seem ed to be above one 
hundred feet. ii then gradually disap- 
peared under the rubbish of the drifted 
part. The rock constituting this wall is 
a calcareous and argillaceous free-stone 
disposed into layers, of which the section 
only is visible; they degenerate into 
marl, and, finally, into clay, by the ac- 
tion of water. The parts most accessi- 
* There was formerly on this summit a 
fort, which served for an advanced post in the 
ancient'wars which the Swiss sustained against 
the Austrians. Though M. S. went to the 
spot. he could not discover the slightest ves- 
tiges of masonry, or buildings of any kind, 
He was, notwithstanding, assured by others 
that some traces still temain i“ 
¥ This indication is correct on! ly as it ‘re- 
lates to the scil near the summit, for in that 
place alone\zhere was pressure without fallin g 
towards the ‘Lettom of the valley. 
Account of the Fall of Ruffiberg, in Switzerland. 
[July t, 
ble to this liquid are clay. Those ta 
which it cannot insinuate itself are free- 
stone, generally speaking; for the diffe- 
rent layers are not alike susceptible of 
decomposition. Their plane in the top 
of the mountain descends towards the 
bottom of the valley, parallel to the slope 
of Rufiberg, under an angle of twenty- 
five degrees. This angle is least towards 
the middle and lower part of the moun- 
tain, for its siope from the bottom to its 
summit has the form of an arc, whose 
chord must be supposed to be up in the 
air. This wall, and all the beds of which 
it is formed, are split transversely to the 
direction of the fallen part by large and 
almost vertical clefts. 
The layers of free-stone and clay are 
contiguous. ‘There may be seen, how- 
ever, “between them, just below the sum- 
mit, a layer of pulverulent coal blended, 
with clay. This layer was not above an 
inch thick. The upper part of the cut 
is covered sometimes with vegetable 
earth, and sometimes with great blocks 
of blend, which never mix with the free- 
stone, and are of a, different nature. It 
was in some measure the weight of these 
blocks on the layers of the softened free- 
stone which occasioned their pressing, 
and, finally, theirfalling into the bottom of 
the valley. It is also to be conceived that 
the lower layers were decomposed be- 
fore the upper ones, by the introduction 
of water through the clefts, This liquid, 
after haying arrived at their lower ex~ 
tremity, insinuated itself becween the 
the layers, run parallel to their plane, 
towards the foot of the mountain, and 
decomposed them throughout their whole 
length. 
The vertical section of this cut or 
wall, Jig to its length, appeared to 
be in a great measure owing to a vein of 
calcareaus spar, which cuvers, like a 
varnish, the surface of the wall brought 
to view by the pressure. The vein thus 
cutting vertically several layers of free- 
stone has established between its parts a 
solution of continuity which has oeca- 
sioned a clear fracture, and on a distinct 
plane. 
The west border of the driven cliff ter~ 
minates insensibly, and does not, like the 
east border, present a vertical cut, or 
wall. We shall now notice the space in- 
cluded between these borders, 
- The sumuut of the mountain is an ho- 
rizontal line that unites two planes of 
turf, inclined and supported against each 
other in form of a roof, About a toise 
below this summit, and in an horizontal 
length ; 
