CONCRETIONARY STRUCTURE IN ROCKS — WESTON. 



141 



it is an interesting discovery which should urge those working 

 among the gold-bearing slates of Nova Scotia to a diligent 

 search for organic forms. 



At Dr. Sehvyn's request, the writer spent several weeks among 

 the gold-bearing slates of St. Mary River, the Ovens, and other 

 localities in Nova Scotia. At Cape St. Mary, concretionary forms 

 such as those from the Northup mines, only very much flattened, 

 some to the eighth of an inch in thickness, were seen. Many 

 were broken open and carefully examined, but no trace of 

 organic structure was found. 



In the Cambrian sandstones (Potsdam), on the banks of the 

 Rideau Canal, near Kingston, Ont., large cylindrical trunk-like 



Section of Weathered Specimen. 



concretions stand erect transverse to the bedding of the deposit. 

 Some of these are from ten to twenty feet in height. (See figure, 

 p. 140.) Dr. Selwyn visited these so-called fossil trees, and 



