14 
THE GEOLOGIST. 
his paper, however, in the ' Memoirs of the Geological Survey of 
Great Britain,' the same author speaks of them in a somewhat more 
decided tone as follows : — " Among the pebbles of the new red sand- 
stone conglomerate nearest to Dartmoor, granite from it is scarce, 
some varieties having been only found on the north, by Tawton and 
Sampford Courtney." * 
Geologists, however, have by no means all concurred in this 
opinion respecting the so-called " granite pebbles." Thus we find 
Mr. Godwin-Austen — and probably few geologists are so intimately 
acquainted with the district — in his paper already quoted, expressing 
himself thus : — " In the study of detritic formations the identification 
of mineral fragments becomes of almost equal importance with that 
of organic remains ; in the present instance they afibrd only negative 
testimony; but as, from the absence of volcanic fragments in the 
conglomerate Eocene beds of Central France we infer the relative 
age of the volcanic outbursts of that region, so, as no granite pebbles 
have been found among the various materials of which the new red 
conglomerate is composed, we may conclude, that at the period of its 
accumulation the granite of Dartmoor could not have been exposed, 
particularly when we bear in mind that the two formations are at 
pi-esent separated only by the valley of the Teign. 
The beds of the greensand of the Haldons and the Bovey valley, 
in the thin mica, sharp quartzose crystals and seams of felspar clay, 
suggest that they may have resulted from a decomposed granitic dis- 
trict ; but here again, although fragments of all the older rocks occur 
in the conglomerate beds at the base of the greensand, granitic peb- 
bles are altogether wanting ; nor do we meet with them until we 
arrive, in ascending order, at those superficial accumulations which 
cap the Haldons, when they appear in great abundance associated 
with rolled flints, and worn like marine shingle. Possibly, then, the 
rise of the graiiite of Dartmoor, in its present form, may belong to 
a period comparatively recent." f 
Sir Charles Lyell says, " The granite of Cornwall is probably of 
the same date," (as that of Dartmoor) " and therefore as modern as 
the carboniferous strata, if not much newer. '''X This expression is 
evidently very guardedly indefinite, much more so probably than 
would have been the case had that distinguished author been satisfied 
that the pebbles in question were really granite. 
Happening, a few years ago, to be at Xorth Tawton, I mentioned 
the subject to Mr. William Yicary, theu resident there. He imme- 
diately took me to the conglomerate, and in a few minutes extracted 
two or three pebbles, which we both regarded as certainly of Dart- 
moor derivation. I am not sure that either of us would have con- 
tended that they were true granite, if by that term we arc to under- 
stand a mass made up solely of distinct crystals of felspar, quartz, 
and mica ; nor, thus defined, would any one be prepared to call every- 
* "Memoirs Geol. Survey, vol. i. p. 228. 
t Geol. Trans., 2ad series, vol. vi. part ii. p. 478. 
X ' Manual of Elcmeulary Geology,' 5tli ed. p. 587- 
