636 PROCEEDINGS OF THE NEW YORK MEETING 



The following paj^er was read by title : 



PROBABLE AGE OF THE MEGUMA (GOLD-BEARING) SERIES OF NOVA SCOTIA 



BY J. EDMUJfU WOODMAN 



[Abstract] 



From the earliest studies to the present, the age of this series has been 

 referred to in terms that are either vague or dogmatic without requisite 

 evidence, and has been placed from the Silurian to the pre-Cambrian. The 

 most commonly stated age is Lower Cambrian, the judgment being based (1) 

 on "fossils," (2) on lithological resemblance to other supposed Cambrian rocks. 

 For the most part, recent references have merely stated the age, assigning no 

 reason for the belief. 



The "fossils" are believed to be inorganic and the lithological resemblances 

 untenable as evidence. 



Of the possible lines of evidence not before referred to, graphite, lime, and 

 concretions are of no direct value. Scolithus and certain as yet undescribed 

 trails from Halifax are serviceable only as evidence of organic forms of some 

 undetermined kind. Unconformities show that all the great events in the his- 

 tory of the series are pre-Devonian except the intrusions, which are lower 

 Devonian ; but thus far fail to narrow the problem further. The composition 

 of younger rocks shows detritus from the Meguma in the Devonian and Car- 

 boniferous, but nothing more definite as yet. 



Comparative structures are held to be especially important. The whole Of 

 the peninsula of Nova Scotia is built upon the Meguma series as a base, and 

 the rocks of all ages show some sympfl^'"'" in the strike of their axes, with the 

 very marked orogenlc type exhibited .. uat series. There are no I'ocks on the 

 mainland of Nova Scotia containing Cambrian fossils, and the next age repre- 

 sented by fossils is the Ordovician. These rocks show a different orogenic type 

 from the Meguma ; so different as to lead to the conclusion that the mountain- 

 building of the latter entirely preceded the Ordovician. As the formation of 

 the bedded veins was contemporaneous with the folding in the Meguma, this 

 places the chief features of its histoi-y into the Cambrian or before. 



The thickness of the series (nearly 30,000 feet) is regarded as far too great 

 to be assigned to the Cambrian without anj' direct evidence. The intrusives of 

 the Meguma are all acid and abyssal, except some dioritic material on the 

 northern margin of the great western bysmalith and a few dikes ; and the 

 amount of igneous rock is very great compared with the area of the sediments, 

 one mass alone covering nearly 2.000 square miles. The granites intrude Silurian 

 rocks in Annapolis, Digby, and Kings counties, but are older than the Horton 

 series, mapped as Devonian, in Kings. They were intruded after all the main 

 chapters in the history of the Meguma series had been enacted. No other rocks 

 of the province are characterized thus, the next younger, the Ordovician, having 

 basic hypabyssal types. 



In previous literature correlation, direct or implied, has been made with 

 various series fi'om the Silurian down, those series themselves often of doubt- 

 ful or unknown age. These correlations ai-e regarded as unwarranted, and the 



