Mci:^iiiita Series of Nora Scotia. — ]\'oodiiiau. 31 
cunihcnt scdinu'nt for its growth. Moreover, it is all prc-Car- 
honifcrous. and probably considerably antedates that period. 
The fourth group of testimony conies from the intrusions. 
With the c.\cei)tion of dioritic marginal phases and dioryte 
apophyses, they are all ^granitic and abyssal. Nowhere does 
the slightest tendency ai)])ear toward a transition to quartz por- 
phyry or aporhyolyte; although the granites cut the highest 
strata in the scries in such manner as to show that they must for- 
merly have extended far higher. This is es])ecially true of the 
great western massif. The period of intrusion was afteralmostall 
the great events in the history of the Meguma had taken place ; 
and this indicates tliat even at that time there w^as a very con- 
siderable cloak of superincumbent strata . Some of the granite 
areas are so large as to force the conclusion that they originally 
extended far above the present summit of the series. The depth 
of cover needed to allow acid magmas to crystallize as coarse 
granites must be considerable, as shown by the infrequenc\- of 
dikes of granite ether than as short apophyses. 
The conclusion from these various lines of observation is 
that the Halifax formation must originally have been far thick- 
er than at present, or that it was covered by some thick form- 
ation, probably conformable and sharing its history. The 
great western massif, cutting Siluro-Devonian strata, seems to 
indicate the latter ; but ( i ) these strata are not of great thick- 
ness, and (2) the granites of the Meguma series are almost 
certainly of more than one age of eruptivity, so that the his- 
tory of the large mass cannot fairly be taken as representative 
of the whole. Althoug!i there 'is no direct quantitative evi- 
dence, it probably is safe to consider that at least a mile has 
been stripped from the present highest beds of the Halifax, of 
which we have not even a vestige left. 
Problem of original diiiieiisioiis : present bulk. — The area 
now occupied by the stratified rocks of the series is 4,500 square 
miles. The knoA\n thickness alone, if uniform, gives with 
this area a contents of 22,500 cubic miles before erosion. But 
measurements across the folds show that the same sediments 
now exposed, if restored to a flat position, would occupy at 
least 75 % and probably 100% more area; so that the total bulk 
of tlie rocks now represented, liut restored to an even thick- 
ness may be conservatively estimated at 45,000 cubic miles. 
