MONEYMAN ON THE GEOLOGY OF NOVA SCOTIA. 201 



age, rather questionable. Sir Wm. Logan at first entertained 

 the opinion that the lower Arisaig Series, especially its serpentines, 

 were probably of the age to which I now consider them to belong, 

 but subsequently he changed his opinions. 



There can be no question, however, that marine life was 

 abundant at the period when the rocks of the lower Arisaig series 

 were formed. The extent of the marbles, especially in Cape 

 Breton, proves this. These marbles were doubtless originally 

 fossiliferous limestones which were subsequently rendered crystal- 

 line by metamorphic action. I have already referred to a case of 

 this kind in the metamorphic middle Silurian, near Cape George. 

 The great development of these marbles shows that life then was 

 at least equal in prevalence to that of the lower carboniferous per- 

 iod, and greater than that of the middle and upper Silurian. The 

 latter under the most favorable circumstances, e. g. McAra's Brook, 

 show limestones only in lenticular beds, a few inches in thickness, 

 w^hile the carboniferous has limestones of considerable extent and 

 thickness. 



I have shown that these marbles cannot be metamorphosed lower 

 carboniferous limestones. It is, therefore, a just inference that they 

 belong to another period which is known to have abounded in life, 

 to the lower Silurian which includes the limestones of the Calcif- 

 erous, Chazy and Trenton. 



I consider that the syenites, diorites, porphyries and hornblende 

 rock, are indigenous, i. e. resulting from the metamorphism of 

 sedimentary rocks, belonging to an age preceding the Silurian — 

 Azoic, — that they were subaerial during the Lower Silurian period, — 

 that by the tear and wear of these, the argillites and quartzite were 

 formed, — while at the same time the marine fauna of the period, 

 were actively or passively forming limestone, that all were 

 unitedly exposed to rnetamorphic or hydrothermal action, under 

 pressure, — that the argillites were ' metamorphosed, the ser- 

 pentines formed, and the limestones crystallized, — that the 

 syenites and diorites were then fissured and pervaded with 

 veins of calcite and quartz, — that they were conjointly elevated 

 after the upper silurian and prior to the lower carboniferous period, 

 that they formed islands in the lower carboniferous seas, upon which 



