562 Notices of Memoirs—W. H. Hudleston— 
this great question with characteristic ingenuity, and showed pretty 
conclusively that neither the punching theory nor the absorption 
theory would meet the facts of the case. De la Beche gave us a 
valuable hint, as indeed he was in the habit of doing, when he 
inferred that, owing to the volcanic activities which had prevailed 
in the area during the deposition of the Paleozoic series, a line of 
least resistance to a body of granite, impelled upwards, might have 
been formed. In this way the granite of the great bosses may 
have been forced through ground already weakened as the site of old 
volcanic vents—such as Brent Tor, we might add. 
Of course, it must be remembered that the contacts we now see 
only represent a certain stage in the relations between the granite 
and its case. A million years ago, when the country was much 
higher relatively, the contacts may have presented a somewhat 
different phase, whilst it is certain that those who are able to inspect 
the contacts after another million years of atmospheric denudation, 
will at least get much nearer to the roots of the matter. As far 
as I am able to judge from Mr. Ussher’s descriptions, there are 
indications of a considerable lateral thrust on the north and on the 
south side of the mass, parallel to the mean strike of the enclosing 
beds. This looks very much as if the main displacements which 
took place were lateral, the beds yielding to the pressure gradually, 
and thus helping to intensify the flexing of the district. 
How far the evidence is in favour of Mr. Ussher’s suggestion that 
Dartmoor is a laccolite, insinuated at the junction of Devonian and 
Carboniferous rocks, I am unable to say. This seems a somewhat 
ignominious termination to a career which patriotic Devonians have 
regarded as nothing less than the plutonic supply-pipe of a regular ~ 
volcanic cone, more lofty than that of Etna. Possibly the two 
theories may be reconciled by regarding the supposed laccolite as a 
kind of reservoir, or local thickening in the pipe. 
It was Professor Bonney who first set the Devonshire geologists 
on the look-out for the vestiges of the great Devonshire volcano. 
Not a mere Brent Tor this time, erupting its lavas into the Devonian 
Sea, but one of a line of lofty peaks of far later date. “‘ Among the 
many excellent geologists and enthusiastic students of the West of 
England,” said he, “is there no one who will undertake to replace 
the covering which has been stripped from the granitic bosses ?”’ 
He also indicated that a thorough study of the “red rocks” of 
Devonshire would yield important results in this direction. 
Mr. Worth is amongst those who have responded to this challenge, 
a circumstance to which allusion has already been made in dealing 
with the New Red question. It is somewhat singular that if there 
really was a volcanic cone covering the Dartmoor pipe, the traces of 
it should have to be sought at the eleventh hour in the “red rock ” 
breccias. These ought to be full of unmistakeable fragments of old 
acidic lavas, and of the felsites which are structurally intermediate 
between such lavas and granite. Possibly the want of adequate 
petrographic knowledge may have hitherto retarded the discovery, 
and we naturally await the result of further investigations. 
