470 PARALLEL LINES OF DISTURBANCE AT DIFFERENT EPOCHS. 
gland from the earliest Silurian period to the Carboniferous sera included, — in one 
instance, indeed, to the close of the New Red Sandstone 1 , and in the Ural Moun- 
tains from the Silurian, till after the Permian period, — are facts which it is import- 
ant to record. 
Lastly, if throughout the whole chain of the Ural we can, from the direction of 
the deposits alone, make no distinction as to epochs of dislocation, still less can 
we attempt to do so when we turn to the Timan range, which, though trending for 
500 miles from north-east to south-west, consists, as we have shown, of palaeozoic 
rocks of the same age as those of the Ural ; the only distinction being, that along 
no portion of that low ridge are the Permian deposits affected, as along the south- 
western flank of those mountains. 
P.S. In alluding to the inverted position of strata, we ought not to forget the 
remarkable case cited in North Wales, where along a considerable space in Mont- 
gomeryshire and Radnorshire, the Upper Silurian rocks either dip under or abut 
against what are now known to be Lower Silurian, but which, from want of suffi- 
cient examination, were formerly supposed to be distinct, and were then called 
Cambrian. (See Silurian System, p. 309, and Chap. I. of this work.) 
1 See Silurian System, p. 294 et seq. 
