108 J. E. WOODMAN PROBABLE AGE OF THE MEGUMA SERIES 



ingston contains nothing referable in any way to the Megnma; nor do 

 any other rocks of that age. 



COMPARATIVE STRUCTURES . 



An important line of evidence as to the age of the series relative to 

 other rocks comes from a study of its structure and that of the other 

 series represented in the peninsula. Most of the younger groups of rocks 

 show traces of local east and west or northeast and southwest folding 

 here and there. It would be surprising not to find this; for they were 

 laid down upon the flanks of the Meguma, which stood as a landmass 

 probably to the south, and some folding has naturally taken place roughly 

 parallel with the old land; but of systematic orogenic types of any sort 

 they show nothing directly comparable to that of the Meguma. 



In the region of the Salmon Eiver lakes and West river Saint Marys, 

 the Lower Carboniferous rests on both Devonian and Meguma, and holds, 

 especially near its base, many boulders of quartzite from the latter; it 

 shows obscure northeast anticlines. In a few places the Devonian ex- 

 hibits a tendency to east and west folding, but a vague one. For the 

 most part its folds are imsystematic. The most pronounced lack of agree- 

 ment of the Meguma folds and tliose of other series is in the Ordovician. 

 Some of tlie geological sheets of the province issued by the Geological 

 Survey of Canada (documents 389 and 550) show this well. There is 

 here no parallelism between the axial directions in the two systems; but 

 in this part of N"orth America deposition was not markedly discontinuous- 

 from early in the Cambrian to the end of the Ordovician. Such uncon- 

 formities as have been found are trifling and do not mark a hiatus suffi- 

 cient to allow time for large scale orogenic disturbance. The Ordovician 

 has none of the structural or lithological features that characterize the 

 JMegnma. There are not the north and south faults nor the even east and 

 west folds. 



The difference between the Ordovician and the Meguma in this respect 

 is extremely important. It is not a trifling disagreement in the strike of 

 the beds; it is the difference on the one hand between a type of orogeny 

 characterized by remarkably persistent folds, comparable to those of the 

 Jura and the Appalachians, and on the other hand an almost entire ab- 

 sence of type in the Ordovician. 



Only a few periods of disturbances so severe as to warrant calling them 

 mountain building can be found in this part of the country before the 

 Mesozoic. The Appalachian revolution is outside the present discussion, 

 as shown by the Lower Carboniferous contacts and contents. The next 

 older catastrophe M^as the Acadian revolution, separating the Devonian 

 from the Carboniferous throughout most of Acadia; but the Devonian 



