6 
BULLETIN OF THE NATURAL HISTORY SOCIETY. 
Second — A shallow ocean with strong marine currents — a 
sandy formation. 
Third — A deeper ocean devoid of strong currents, giving a 
fine mud formation. 
Fourth — An open ocean with pure sea-water, having reef 
building organisms; and, as a result, a calcareous mud formation, 
now converted into limestone. 
As yet we have no proof that any part of Acadia was above 
the sea at this time, but it is evident that the sands of the second 
period must have been derived from the waste of some pre- 
existing land not very far away containing granitic rocks. 
The Huronian Phase.* 
We have to contemplate the existence of two terranes in this 
portion of the geological column in New Brunswick — a lower of 
clay slates and magnesian schists and grits with intercalated 
trap beds and levigated eruptives, capped by fine dark argillites; 
and an upper a great and uniform series of volcanic effusives. 
The relations of the different parts of the main or lower 
terrane are more difficult to trace than that of the preceding 
system owing to the softness of the upper member, which is 
usually concealed in the hollows of valleys where it has been 
eroded and subsequently covered up by later terranes of Palae- 
ozoic Age. 
The thickness of this terrane is very great as it may, in some 
places, be crossed for a distance of five miles, showing consecutive 
beds dipping at a high angle. 
As in the Laurentian system we found a great limestone 
member marking a period of rest and slow accumulation, so 
in this there is a mass of fine gray argillites or clay slates, indi- 
cating a time of repose when the earth’s crust was at rest and in 
this region and covered by an ocean of considerable depth. Such 
conditions and such deposits are likely to be wide-spread and 
serve to trace geological terranes from one region to another. 
*In this paper the term Huronian is used for the formations that intervene between 
the terrane just described and the base of the Cambrian System. 
