58 
SCENERY OF SWITZERLAND. 
action. When the two are associated, as in the 
Andes, the volcanoes are due to the folding and 
crushing, not the folding to the volcanoes. 
The Alps then have not been forced up from 
below, but thrown into folds by lateral pressure. 
This view was first suggested by De Saussure, worked 
out in fuller detail by Sir Henry De La Reche in 
1846, and recently developed by Ball, Suess, and 
especially by Heim.* 
Moreover, as the following sections show, (Figs. 1, 
5, 23-26) we have every gradation from the simple 
undulations of the Jura (Fig. 5) to the complicated 
folds of the Alps (Figs. 1, 23-26). 
But why are the surface strata thus thrown into 
folds? When an apple dries and shrivels in winter, 
the surface becomes covered with ridges. Or again, 
if we place some sheets of paper between two weights 
on a table, and then bring the weights nearer to- 
gether, the paper will be crumpled up. 
In the same way let us take a section of the 
Earth’s surface A B (Fig. 2) and suppose that, by 
the gradual cooling and consequent contraction of 
the mass, A B sinks to A 1 B 1 , then to A 2 B 2 , and 
* See especially Heim’s great work, Untersuchungen it. d. 
Mechanisnms d. Gebirgsbildung. I ought perhaps, however, 
to add that this view is not universally accepted. 
