THE MOUNTAINS OF SWITZERLAND. 89 
with pebbles of granite, gneiss, or crystalline schists, 
but deep-sea deposits of fine sediment evidently 
formed at some distance from land. In the Triassic 
period there seems to have been a barrier between 
the Eastern and Western Alps, but subsequently the 
conditions must have been very similar, and the 
southern shores of the Jurassic Sea were perhaps far 
away in Africa.* 
Even the Eocene deposits show no evidence of a 
shore where the Alps now rise above them. 
We have other proofs that the central chains 
were formerly covered by other strata. For instance, 
the Puddingstone of Valorsine at the head of the 
Chamouni valley, which belongs to the Carboniferous 
period, contains no granite or porphyry pebbles. The 
granite and porphyry strata of the district must there- 
fore at that period have been protected by a cover- 
ing of other rocks which have been since stripped off. 
It is also significant that the pebbles of the Mio- 
cene Nagelflue which come from the neighbourhood 
are mainly of Eocene age. Neither the Crystalline 
rocks nor the older Secondary strata seem to have 
been then as yet uncovered.** There are indeed 
* Heim, Meek. d. Gebirgsb vol. H.; Baltzer, Beitr. z 
Geol. K. d. Schw L. xxiv. 
** Heim, Mech. d. Gebirgsb ., vol. II. 
