6-t BULLETIN OF THE NATURAL HISTORY SOCIETY. 



and those having a variety of terchratula, evidently belong to 

 the imperfect coal measures, of whicli there are several instances 

 in the province."* 



One basin of such imperfect coal-measures is that of Lepreau 

 described hj Dr. Gesner ; f another is that of Quaco. 1 Dr. Gesner 

 believed that both of these basins were of Carboniferous age. 



If my interpretation of Dr. Gesner's views of the age of the 

 Upper Graywacke group is correct, he expressed successively the 

 following opinions of the age of these rocks : 



In the First Report — Transition. 



In the Second and Third Reports — Silurian. 



In the Fourth and Fifth Reports — Cambrian. 



T ^1 .r -v^ -r. • 1 )> ( Part of them are called imperfect 



in the "JNew Urunswick, — , '■ 



I coal measures. 



One more phase of opinion is that expressed in Dr. Jas. 

 Robb's geological map of New Brunswick, Avhere these rocks are 

 colored as Upper Silurian. In all this time, from 1838 to 1860, 

 no actual progress had been made in determining the true age 

 of these strata. The first important step in this direction was 

 taken when Sir Wm. Dawson, by the study of the plant remains, 

 showed that the upper part of the group was at least as old as 

 the Devonian ; and the second, when Prof. C. F. Hartt found, 

 by comparison of the moUusca with those of the Primordeal 

 Zone, of Barrande, in Bohemia, that the lower part was 

 Cambrian. 



The unravelling of this complex Pre-carboniferous massif oi 

 southern New Brunswick has not only shown that it contains 

 the plant- bearing terrane and the Primordeal terrane above 

 mentioned, but three others in addition, besides the " funda- 

 mental gneiss," so that there is ample room for deposits of all 

 the eras to which Gesner and Robb referred it. 



*New Brunswick, p. 343. + First Report, p. 52. J Second Report, p. 15. 



