102 
SCENERY OF SWITZERLAND. 
and indicate therefore the presence of former moun- 
tains. 
The pebbles consist principally of primitive rock, 
mainly Gneiss, but comprise no Granite or Porphyry, 
so that these rocks cannot then have been exposed, 
but must have been covered and protected by other 
strata. The pebbles are mixed with Quartz and 
Mica embedded in a hard reddish cement. Blocks 
of this Puddingstone, as already mentioned, have 
been transported by the glacier to a great distance. 
It was well studied and described by De Saus- 
sure in 1776 at Ceblancs, on the north of the 
mountain Les Posettes, where the layers are vertical, 
while, as he remarked, they must have been hori- 
zontal, or nearly so, when originally deposited. “II 
faut done regarder,” he says, “comme une chose 
demontree, que ces poudinges ont ete formes dans 
une position horizontale, ou a peu pr^s telle, et re- 
dresses ensuite apr^s leur endurcissement,” This im- 
portant observation was the first proof of the eleva- 
tion of Sedimentary strata. * 
However self-evident this may appear to us now, 
it seemed extraordinary at the time, and Bertrand 
even attempted to show that the pebble beds might 
have been deposited in a vertical position! 
* Favre, Jiech. Ge'ol., vol. II. 
