224 Messrs. Hicks and Davies— 
which, however, are approximately parallel to the plane of 
foliation.—T.D. ] 
No one, I think, can read Mr. Davies’s descriptions of the rocks 
15 and 14, and 21 and 22, which mainly make up what I consider 
the Pre-Cambrian floor along this line, and not realize that they are 
petrologically very unlike those described by him in his Notes 15-20, 
from the higher beds along the same line. The latter in all cases, 
it matters not from what part they are selected, always contain 
fragments unchanged, and have their detrital origin still well 
marked; whilst the former are always crystalline throughout, and 
retain little or no indication of their original condition. It has been 
supposed by some, since I first pointed out this discordance in the 
strike of the upper and lower rocks in Glen Docherty, that it is 
entirely due to faulting, and that the upper beds with a low angle 
of dip and a N.E. strike have been twisted so as to appear below at 
the high angle and with a N.W. strike. If this occurred at one 
point, or for a short distance only, it might perhaps be possible ; but 
that it should extend for several miles, and include both sides of the 
Glen, is, I venture to say, highly improbable, if not utterly im- 
possible; and those who have made the suggestion could not, I 
think, have attempted to realize the physical difficulties of such an 
occurrence. Moreover, as explained above, the petrological evidence 
also is opposed to such a view. 
I have to express some regret for having allowed the section in 
my former paper to appear without a fuller explanation, though I 
clearly stated in the discussion that it was “a rough diagrammatic 
one,” and that the angle at which the beds were drawn was much 
too high. The dip intended to be shown also was only for the 
escarpment in Glen Laggan, and its continuation at that angle east- 
ward was a pure mistake. Section IJ. in the present paper, taken 
further south in Glen Laggan than the former one, and more imme- 
diately along the Glen Docherty heights, will explain more clearly 
what was there intended to be shown. JI believe, however, that few 
only of those who read my former paper intelligently have found any 
difficulty in realizing what was meant; but as some have appa- 
rently failed to comprehend what was intended, I trust the present 
illustrations will enable them to do so. The following passage, taken 
from my former paper,’ appears to me sufficiently explicit on this 
point, and should have prevented any misapprehension, though the 
section was accidentally distorted :—‘The question as to how the 
Silurian rocks could have been brought into the positions indicated 
in the latter part of the section, is a difficult one. Is it the result of 
a natural overlapping of the older rocks eastward by these newer 
rocks? or have they been brought into this position by faults? I 
saw no evidence of faults of sufficient magnitude to bring them to 
this position alone; but minor faults there are undoubtedly, and 
these have in some cases considerably altered the position of some of 
the beds. On the whole, however, the evidence seems to show that 
these Silurian beds have been deposited on the eroded edges of the 
1 Quart, Journ. Geol. Soc. vol. xxxiv. p. 816. 
