26 
SCENERY OF SWITZERLAND. 
of debris, but especially because the rocks have been 
subjected to such extremes of heat and pressure 
that not only have the fossils been altered, and often 
entirely destroyed, but the very rocks themselves 
have been bent, folded, reversed, fractured, crushed, 
ground, and so completely metamorphosed that in 
many cases their whole character has been changed 
beyond recognition. 
Igneous Rocks.— Gneiss. 
To commence with the Igneous series, which 
come from the fiery heart of the earth. Gneiss, 
which is in Switzerland as elsewhere the fundamental 
rock, forms in great part the central ranges, reap- 
pearing also here and there in other parts, as for 
instance on the Rhine at Laufen, and would, it is 
thought, be found everywhere if we could penetrate 
deep enough. 
Gneiss is composed of Quartz, Felspar, and Mica, 
with a more or less foliated structure. The Felspar 
is generally white, but sometimes green or pink, and 
has often a waxy lustre; the Mica is white, brown, 
or black. The Quartz forms a sort of paste wrap- 
ping round the other ingredients. 
Gneiss presents the same general characters all 
over the world. It is not all of the same age, and 
