Section IV., 1909. [67] Trans. R. S. C 



YI.— The Geological Age of the Little River Group. 



By G. F. Matthew, D.Sc, LL.D. 



(Read May 26, 1909.) 



With the discovery of new species of plants in the Little River 

 Group, has come the need of re-examining the geological evidence of the 

 age of this terrane. 



For many years the decision of Sir J. W. Dawson, based upon a 

 study of its plant remains, that the terrane was Devonian, has been 

 accepted by most geologists, but of late years eminent palseophytologists 

 have announced that the evidence of the plants is not to be read that 

 way, but that these plants indicate tliat the deposits in which they are 

 found must b^ of Upper Carboniferous age. To the author, who has 

 studied the stratigraphy and lithology of the terrane, such a determina- 

 tion seems inadmissible, and he has therefore outlined briefly in this 

 article the evidence, which points to a higher antiquity. He proposes to 

 consider the question chiefly from three points of view :— 1st The rela- 

 tions of supraposition and infraposition, 2d the amount of metamor- 

 phism in the terrane, and 3d the comparison of it with neighbourikig 

 series of strata the age of which has been determined by marine organic 



remains. 



It unfortunately happens that this terrane (limited by the area 

 where well-marked remains of land plants are found) contains no marine 

 deposits, such as in other countries are interleaved with the strata that 

 contain land plants, and so the evidence of contemporary marine organ- 

 isms is wanting ; we have therefore to depend on less direct evidence for 

 the age of this terrane than would have been the case if the terrane had 

 contained fossiliferous strata of marine origin. 



1. Relations of supraposition and infraposition. 



To make the remarks under this head more intelligible the writer 

 has prepared a geological sketch-map of the district where the terrane is 

 spread, to show its relations to the surrounding terranes, most of them 

 of greater antiquity. He has also drawn a section crossing the main 

 basin of these rocks, from St. John to Cape Spencer, along the eastern 

 side of St. John harbour, which shows their relation to the underlying 

 and overlying terranes. This section will be found on plate TV. of the 

 article on Remarkable Forms of the Little River group. 



The core of the geological deposits in this district is a set of gneisses 

 and limestones that has been cut by old intrusions of quartz-diorite or 

 syenitic granite which itself as well as the above clastic rocks, has been 

 cut by dark fine-grained diorites. The whole together formed a rigid 



