217 



From the above view points, Fletcher made use of five 

 main arguments to show that the Riversdale-Union and 

 associated strata are of Devonian and not Carboniferous 

 age as held by various palaeontologists. It should be 

 remembered that of the contending parties, Fletcher is 

 virtually the only member who has studied the strati- 

 graphy of the region. Fletcher held that the strata in 

 question are of Devonian age because: (i) The measures 

 as compared with the Carboniferous beds, are in general 

 metamorphosed, contorted, and associated with igneous 

 rocks generally absent from the Carboniferous areas. 

 (2) The measures contain fossil plants, etc., of Devonian 

 types. (3) The measures closely resemble the Little 

 River group of St. John, N.B., which by Dawson was 

 placed in the Devonian. (4) The measures cannot lie 

 above the Limestone series since they are not developed in 

 such well defined sections as those of Joggins and Sydney 

 harbour. (5) The measures lie unconformably beneath 

 the Carboniferous Limestone series. 



As opposed to the above arguments it may be urged: 

 (i) That, deductions based on relative degrees of metam- 

 orphism and of disturbance of the strata and on the pre- 

 sence or absence of igneous bodies, are not always reliable 

 since by using such arguments, Fletcher [5] in the case of 

 one area, grouped in the Devonian certain metamorphosed, 

 disturbed, fossiliferous limestones and associated beds cut 

 by igneous rocks but later [6, p. 33 and pp. 44-45; 7], 

 in spite of their evident metamorphism and disturbed 

 condition, placed them with the Carboniferous and stated 

 [6, p. 54] that some of the Carboniferous strata are as 

 much altered as the so-called Devonian. (2) That, though 

 the assemblage of varied measures grouped by Fletcher as 

 Devonian do hold Devonian fossils in places yet this is 

 only so because the so-called Devonian is made up of 

 diverse elements including the fossiliferous lower Devonian 

 of Arisaig. But the bulk of the strata, so far as the fossil- 

 iferous evidence goes, is held by palaeontologists to be of 

 Carboniferous age and to include measures representative 

 of the Horton series at the base of the system and of horizons 

 about equivalent to the Millstone Grit in the upper part 

 of the system. (3) That, the bulk of the so-called Devon- 

 ian may represent the Little River group of St. John, N.B., 

 is generally conceded but though Dawson assigned the 

 Little River group on palseontological evidence to the 



