THE OUTER-ALPS. 
51 
CHAPTER XIII- 
THE OUTER-ALPS. 
The outer chain of the Northern Alps consists of 
Eocene and Secondary strata thrown into a series of 
folds, and running from SW. to N.E. They extend 
far into Austria on the east, forming the north part 
of the Voralberg, and into Savoy on the west, but so 
far as Switzerland itself is concerned they commence 
in the valley of the Rhine at the east end of the 
Lake of Constance, form the Sentis Mountains, aiid 
the Churfirsten over the Walen See, extend by Ein- 
siedeln and Schwyz to the Lake of Lucerne, stretch 
away to the Lake of Thun, and then form a grand 
curve with its convexity northwards, reaching almost 
to Fribourg, and so to Vevey and Montreux on the 
Lake of Geneva, to the south of which they extend 
into the Chablais and Savoy. 
They form a complicated network, which on an 
ordinary map shows no regular arrangement; the 
configuration of the surface has been greatly affected 
by folds, fractures, faults, and denudation, and the 
structure is in many places still an enigma.* 
* Schardt, “ Struct. Geol. des Prealpes,” Afi. (Geneve) 1892. 
4 * 
