6o 
SCENERY OF SWITZERLAND. 
over such a ridge, and they suggest therefore that 
the watershed was once considerably to the south of 
its present line. We shall find other evidence in 
corroboration of this interesting fact. 
3. Others of the pebbles differ from any rock 
now found m situ. It has been suggested that this 
is because since their removal the parent rocks have 
been so compressed and contorted that their char- 
acter and structure have been materially altered. 
Ihe features presented along the line of contact, 
between the Miocene and Eocene, present much dif- 
ficulty, and have given rise to various hypotheses. 
The strata are generally conformable, but this is by 
no means always the case; for instance the Miocene 
strata of the Rigi abut against the steeply inclined 
Eocene and Cretaceous beds of the Vitznauerstpck 
(Fig. 85). These cases have been accounted for by 
supposing certain districts to have sunk, and great 
overthrusts to have taken place. 
Buickhardt explains the general concordance, 
and occasional cases of discordance, by supposing 
that m the latter the Miocene strata were deposited 
in deltas. For instance, Fig. 86 is a diagram re- 
presenting a deposit of Miocene strata in a delta. 
Now suppose a fold to take place, we should have 
the arrangement shown in Fig. 87. If then sub- 
