HOPKINS ON THE LAKE DISTRICT. 73 
when these beds, and therefore the surface of junction and our ima- 
ginary continuation of it, were all in their original horizontal position, 
below the surface of the sea, those portions of the grauwacké group 
which now constitute the highest summits of the mountains were at 
a lower level than the surface of junction, in which case we should 
necessarily conclude that the deposition of limestone originally ex- 
tended over the whole central area of the district. 
It appears to me extremely difficult to avoid this conclusion, unless 
we adopt some arbitrary and improbable hypothesis respecting that 
elevation of the central portion of the district which must necessarily 
have accompanied that of the mountain limestone now surrounding 
it, or deny the general truth of the conclusion respecting the original 
horizontality of sedimentary beds. Assuming this horizontality, let 
A B represent a stratum before its elevation. The portions A C, B D 
have been elevated into the positions A c, B d respectively, as shown 
e Fig. 1. 
A Cc E D B 
by the present position of the limestone beds, and the question is, 
whether the central portion C E D was raised into the position ¢ e d 
ore fd. Of this we can obtain no direct evidence from observation, 
because the beds occupying the central portion of the district have 
not derived their actual positions from the movement of which we are 
now speaking. We are obliged, therefore, to have recourse to the 
analogy of similar cases of elevation in which the evidence is complete. 
Arguments deduced from such analogy must, I conceive, be almost 
entirely in favour of the view which would represent A ced B, and 
not A cf dB, as the disturbed position of the line of which A B was 
the undisturbed position. In such case, though the inclination from 
e to e and from d to e be allowed to be considerably less than that of 
the limestone from A to ¢ and from B to d respectively, still the whole 
district must necessarily have been beneath the surface of the ocean 
at the time of the commencement of the deposition of the mountain 
limestone. 
6. It might be contended perhaps that these limestone beds were 
not, in the proper sense of the term, sedimentary, but originally formed 
like coral reefs. Supposing such to be the case, the argument above 
adduced in favour of the original horizontality of sedimentary beds is 
equally applicable. I regard that argument as one of the highest 
importance in the fundamental reasonings of Physical Geology. The 
exact point to which it may be urged cannot yet be asserted, from our 
want of more accurate knowledge of the power of animals inhabiting 
the ocean to accommodate themselves to different degrees of fluid 
pressure. It should be recollected, however, that the truth of the ar- 
gument does not depend on any impossibility of the more profound 
depths of the ocean being inhabited, but on the improbability that 
