18 
THE GEOLOGIST. 
here and there at very long intervals. I will not undertake to say 
that it contains no limestone detritus, but I certainly have never 
seen or heard of a fragment of the kind, though I have frequently, 
and with considerable care, examined the gravel, and questioned the 
men who work amongst it ; yet the limestone is one of the oldest 
rocks of the district. Accepting this negative evidence as trust- 
worthy, it simply proves that the direction of transportation was not 
from the south ; not that the rocks in that direction have been called 
into existence since Bovey Plain received its surface covering. 
But to return. The facts now^ in our possession appear to compel 
the belief that the Dartmoor granites were not in existence when the 
carboniferous rocks of Central and North Devon were deposited, but 
did exist and were exposed at the surface in the red conglomerate era. 
In relation, then, to the stratified rocks of the county, we have both 
an ancient and a modern chronological limit for the granites. Our 
next question is, AVbat are the places of the limiting rocks in the 
chronological series of the geologist ? 
There is no difficulty as to the answer respecting the ancient limit 
— the carboniferous beds. Professor Sedgwick and ISir K. I. Mur- 
chison, in their paper already quoted, say the flora of the- upper 
culms, as far as it has been ascertained, agrees specifically with the 
known flora of the Carboniferous period. We think we have strong 
direct evidence to establish our position that the upper culm strata 
of Devon are the geological equivalents of the ordinary British coal- 
fields."* The same authors, in a passage previously quoted, state 
that " the upper division of the culm series contains fossils identical 
with those in the upper division of the coal-measures." 
It is not so easy to settle the modern limit — the red sandstones 
and conglomerates. That they belong somewhere between the Car- 
boniferous and Jurassic systems there can be no doubt, since they 
overlie the culmiferous beds and pass under the Lias ; but w^hether 
they are Triassic or Permian has not been considered so certain as 
could be desired. They are entirely destitute of fossils, excepting 
those only wliich occur in the calcareous pebbles, which, of course, 
belong to the age of the parent limestone. The sandstones are evi- 
dently of littoral origin ; their surfaces frequently display wave-r\\>^\e 
marks, desiccation cracks, and impressions of rain-drops ; but no foot- 
prints or other organic traces iiave ever been detected on them ; 
they apparently contain no palaeontological evidence whatever of 
their age. 
More than one eminent geologist has been struck with the angular 
character of the fragments composing the so-called conglomerate, 
— more correctly, breccia, — and has remarked that in its physical 
character and general appearance the formation is rather Permian 
than Triassic. It is, however, as is well known, coloured on our 
geological maps as being on the horizon of the lower Trias. I am 
not without hopes than the granite pebbles so frequently mentioned 
here may help to shoW' that this decision is correct. 
* Geol. Trans., 2nd series, vol. v. part iii. p. 682. 
