218 Dr. H. M. Ami — The Dictyonema Slates of JYova Scotia. 



Vn. — The Cambrian Age of the Dictyonema Slates of New 

 Canaan and Kentville, Nova Scotia. 



By H. M. Ami, M.A., D.Sc, F.G.S., of the Geological Survey of Canada. 



IN his " Acadian Geology " (1868, 2nd ed., p. 563) Sir William 

 Dawson figures Dictyonema Websteri and places it as a Silurian 

 (Upper Silurian) species. In describing the slates from which the 

 type-specimens of this species were obtained he writes : — "Passing 

 from the Cobequid Mountains to the slate hills of the south side 

 of the Bay" (meaning the Bay of Fundy), "in King's County, 

 we find slates not very dissimilar from those of the Cobequids " 

 (which he had described on the previous page, 562), "in the pro- 

 montory northward of the Gaspereau Eiver. Here the direction 

 both of the bedding and of the slate structure is N.E. and S.W. ; 

 but the planes of cleavage dip to the S.E., while the bedding, as 

 indicated by lines of different colour, dips to the N.W. These slates, 

 with the quartzite and coarse limestones, are continued in the hills 

 of New Canaan, where they contain crinoidal joints, fossil shells, 

 corals, and in some beds of fawn-coloured slate beautiful fan-like 

 expansions of the pretty Dictyonema, represented in fig. 196 ; very 

 fine specimens of tliis fossil were found by the late Dr. Webster 

 of Kentville. It was the habitation of thousands of minute polypes, 

 similar apparently to those of the modern Sertularia. The general 

 strike of the rocks in New Canaan is N.E. and S.W., and they 

 extend from that place westward to the Nictaux River. Westward 

 of Nictaux River, as already mentioned in describing the Devonian^ 

 the beds of the Upper Silurian, as well as those of the last-mentioned 

 formation, are interrupted by great masses of granite which form 

 the hills along the south side of the Annapolis Eiver, from a place 

 called Paradise to Bridgetown, and with some interruptions nearly 

 as far as the town of Annapolis." 



In my " Synopsis of the Geology of Canada," ^ the following 

 paragraph refers to the Silurian of the region in question as 

 presented and systematized from available information : — "In 

 the County of Annapolis, Nova Scotia, and in the vicinity of 

 Nictaux, Silurian strata occui', including the Nictaux iron-ore beds 

 and the Torhrooh sandstone formation, whilst near Kentville the 

 Kentville formation is seen as well as on Angus Brook in the 

 Gaspereau valley, also at New Canaan with Dictyonema Websteri, 

 Dawson," Slates holding Dictyonema Websteri, Dawson, are thus 

 known to occur (1) at New Canaan, N.S., the type locality' 

 (2) at Kentville, N.S. ; and (3) on the north slope of the South 

 Mountain, along the upper portion of the valley of Angus Brook,^ 

 a small stream entering the Gaspereau River between the village 

 of Gaspereau and the Avon River shore. 



Heretofore, the slates which have yielded the specimens of 

 Dictyonema Websteri have been invariably referred to the Silurian 

 system, but more recent examination of the type-specimens of 



1 Trans. Eoy. Soc. Canada, 1900-1901, ser. ii, vol. vi, sect. 4, p. 203. 



