20 
THE GEOLOGIST. 
poi'pbyritic mass subsequently to its consolidation ;* then followed 
the period of denudation ; but all this was anterior to the com- 
mencement of the conglomerate era, since pebbles of each kind of 
granite occur in the Haldon beds, wliich belong to the base of the 
red rocks of Devonshire. 
Should it be objected that the granites, though requiring great 
pressure, were not necessarily formed beneath an accumulation of 
rocky matter, but possibly under an equivalent depth of sea, it does 
not appear that this can greatly affect the chronology of the question, 
at least by way of abridgment. Passing by all other considerations, 
we should require a lapse of time sufficiently great to carry down the 
area of, at least, central Devon, from the relatively high level at 
which the culmiferous beds were certainly deposited, to an ocean 
depth of enoi-moLis profundity ; and time enough, too, after the plu- 
tonic masses had, at this depth, been called into existence, to bring 
it up again within the influence of the waves, so that they might 
detach samples of each kind of granite, to be transported to where 
the conglomerate was being formed. 
Take what view of the case we may, an enormous period between 
the culm and conglomerate series appears inevitable ; a period during 
which great changes were effected within, and on, the crust of the earth 
— changes which, from their nature, could not have been contempo- 
rary, but must have followed each other in a definite and ascertained 
order, and the greater part of which at least convulsion or cata- 
strophe must have been powerless to produce or hasten. 
Unless we assume that a great chronological interval elapsed be- 
tween the Carboniferous and Permian periods, — and to this palaeon- 
tology appears to give no sanction,t — the facts of the case before us 
seem to require the belief: — 
1st. That the granites of Dartmoor are not older, at most, than 
the close of the Carboniferous period. 
2ud. That they had been stripped bare by denudation when the 
materials of the red conglomerates were being brought together. 
3rd. That the red conglomerates and sandstones are not of higher 
antiquity than the Lower Trias. 
4th. That the Permian period was of great duration. 
ON THE MODE OF EOEMATION OF LIMESTONE 
BANDS. 
By Eev. J. D. La Touche, StoTcesay, Salop. 
With a Note ly J. W. Saxtee, F.a.S., A.L.S. 
The existence of layers of limestone at various intervals among the 
rocks, while in the intermediate strata there is a remarkable defi- 
* Trans. Geol. Soc, 2nd series, vol. vi. part ii. p. 477. 
t Page's ' Past and Present Life of the Globe,' p. 114. 
I 
