CENTRAL MASSIVES, 
79 
had forced up, and were therefore younger than the 
Secondary strata. As already mentioned, however 
(a7ite, p. 55), they are now regarded as essentially 
passive, not active; not as having forced up the 
Secondary rocks, but as having been forced up with 
them by the same lateral pressure; as being of ex- 
treme antiquity, and indeed in the opinion of some 
geologists as part of the original crust of the Earth. 
Some, indeed I believe most, geologists consider 
that the Crystalline rocks had been not only de- 
nuded, but also much folded before the deposition 
of the Secondary strata; other great authorities, as 
for instance Heim, dispute this; they believe that the 
earlier folding was comparatively slight, and that in 
the main the folding of the Gneiss and the Secondary 
strata was simultaneous. 
The Central Masslves, the Mont Blanc Massif, the 
St. Bernhard, Monte Rosa, Aar, St. Gotthard, Adula, 
etc., are at present more or less completely de- 
tached. 
It has long been a question whether these moun- 
tain masses should be regarded as independent 
centres of elevation or as parts of a general system. 
As long as mountain chains were regarded as having 
been thrust up from below by volcanic action, the 
former view seemed most probable. 
