JFas Mount Royal an Active Volcano '? 325 



Of this he apportions 5,000,000 for the Azoic or 

 Archsean, the same period to the Eozoic, and 6,000,000 to 

 the Palaeozoic, inchiding the carboniferous or coal period. 



If the Hudson Eiver formation was completed about 

 the middle of this period of 6,000,000 years, which other 

 circumstances would render probable, it would place the 

 eruption as having occurred about 7,000,000 years ago, 

 but, as already stated, this, as well as any other date which 

 might be named, is altogether conjectural, and may be 

 very far from the fact. 



What were the conditions under which the various 

 formations up to the Hudson Eiver were deposited ? 

 Probably a shallow sea, with a slow but quiet and contin- 

 uous subsidence of the land, followed at the end of this 

 period by a contrary movement, which was continued 

 until it stood at possibly a higher level than at present. 



As a possible consequence of this movement of eleva- 

 tion, the great fracture or line of disturbance, which, 

 according to Sir William Logan, has been traced for a dis- 

 tance of 180 miles, from the Hills of Brome and Shefford 

 to the Lac des Chats, on the Ottawa Eiver, and which is 

 marked by the Mountains of Brome, Shefford, Yamaska, 

 Eougemont, Beloeil, Montarville, Mount Eoyal and Eigaud, 

 while Mount Johnson or Monnoir, situated to the south of 

 Beloeil, apparently belongs to the same series, although 

 out of the range of those first mentioned. 



Alonff the line of this fracture or disturbance, at various 

 places where the overlying strata had been weakened or 

 forced apart, liquid or viscid matter was forced upwards 

 until the cavity in the strata was completely filled, in some 

 places, as in the quarry on Cote des Neiges Hill, tilting up 

 and curving the limestone strata and leaving it lying at 

 an angle against the intruded mass. Where the fracture 

 reached the surface, the lava, if the eruption was without 

 violence, would How out over the surrounding country, 

 forming sheets or floors, as in the Indian Deccan, where 



