Correspondence. 285 
rials. Now, supposing the denudation to have been slow, we should 
expect to find similar deposits of limestone and shale formed from 
the denuded matter; or, supposing the denuding agency to have been 
strong and the action violent, in that case we should expect frag- 
ments and boulders of limestone, and their embedded fossils, together 
with the solid organisms from the shales, in the redeposited strata. 
Jam bold to say, however, that throughout the whole region referred 
to, the search would be vain for any such deposits, or beds contain- 
ing redeposited Carboniferous fossils, while the surface-drift does 
not contain such a proportion of calcareous elements as would lead 
us to favour such a theory: indeed, the whole mass of Drift is not 
more than might be expected to result from the scooping out of the 
Welsh valleys, mixed up, as it is, with the materials derived from 
the north. Or, if it should be urged that the redeposited matter has 
been so acted upon by chemical or other agencies as to destroy its 
identity, or that it has been carried away nobody knows where— 
both of which are extreme propositions,—is it at all likely that the 
solitary remnant of the Carboniferous rocks which once covered the 
district referred to would be the outlier at Corwen? Is it at all 
likely that, while all the surrounding strata were swept clean away, 
this little patch would be left intact, to the very top of the series ?— 
would there not in sheltered spots linger relics of the old time to 
tell of that which once had been? May we not have reason to 
expect that, mixed up with the local Drift of the Welsh valleys, 
there would be no lack of Carboniferous débris? Is it at all likely 
that over so extensive a district ‘the house would be swept so 
clean’ as not to leave even a faint trace of its former inhabitants ? 
Yet such is literally the case, if this theory be true. Once passing 
the outcrop of the main ridges, which, like a line of reefs, sweep 
round the eastern and northern sides of North Wales, you fail to 
discern fragments of the Carboniferous rocks in the local Drift, and 
not a trace of this supposed Carboniferous envelopment occurs in 
situ, save the outlier at Corwen. It may scarcely be admissible as 
evidence, but I cannot help saying that the general contour of the 
country, and the appearance of the present limestone escarpments, 
bold and well defined to the very top, capped as they are with their 
shale and fossiliferous beds, and overlying hills of Millstone-grit, 
are incompatible (to my mind at least) with the idea that a whole 
Carboniferous system has been swept away over their heads. 
From these, as well as other considerations, though I too may be 
exposed to the charge of being narrow, and of cherishing ‘auld 
warld’ notions of Geology, I must for the present look upon the 
plain about Corwen as having been once a little inland sea, in which 
the deposition of the limestone of the outlier went on simultaneously 
with that of the main band, but apart from the latter. 
The search for fossils will be most successful in the shale-beds, 
both ém sié, and in the ‘heaps’ into which these have been thrown 
out of the way of the quarrymen. 
Yours, &c. D. C. Davigs. 
OswESTRY, 
