GENERAL SUMMARY. 
251 
is not the case : indeed these rocks contain no pebbles 
of any kind, and the fossils in them are indicative 
of deep water some distance from land. There are 
no conglomerates or gravel beds between the Permian 
and the Upper Eocene. Again (2) we find remains of 
the Secondary strata protected in the troughs of the 
folds. These sedimentary deposits therefore extended 
completely over the site of the present mountains, and 
though no extensive remains of these strata now 
occur in the Central Alps, this is because they have 
been entirely stripped away. 
The elevation of the country was due, not to up- 
heaval from below, but to lateral pressure owing to 
the cooling and consequent contraction of the earth. 
It has been calculated that the strata between Basle 
and Milan, a distance of about 130 miles, would, if 
extended horizontally, occupy 200. There has con- 
sequently been a shortening of no less than 70 miles. 
For some time the central ranges alone were 
above the water, and the mountain torrents brought 
down gravel and boulders, forming the “Nagelflue” 
of the Rigi and the Central Plain. 
The Alps therefore, from a geological point of 
view, are very recent. Our Welsh hills, though com- 
paratively speaking insignificant, are far more ancient. 
They had been mountains for ages and ages before 
