DURATION OP FOLDING. 93 



are unconformities. That near Kuan-yiian-hien is overlain by limestone 

 which may be Permian or Rhaetic, as already stated. But west of Ja-chou* 

 the Mesozoic sediments are conformable to the underlying Devonian and 

 are folded with it. Hence Loczy infers that the folding continued longer in 

 the latter region. It is possible that the vicinity of Ja-chou was outside the 

 zone of Permo-Mesozoic folding, as most of the Red Basin was, and became 

 involved in disturbance only when the Himalayas were compressed in the 

 great post-Eocene epoch of diastrophism. In the zone of the great mountain 

 chains of northern India, the Permo-Mesozoic movement was manifested 

 only in variations of sediment, not in folding. 



*Reise des Grafen Sz^chenyi, L6czy, vol. I, p. 690. 



