142 CONCRETIONARY STRUCTURE IN ROCKS — WESTON. 



caused a section of one four feet in diameter to be sent to the 

 museum in Ottawa. 



The M^riter also saw these singular bodies, and assisted in 

 getting good photographs of them. Weathered transverse 

 sections show well-defined concentric rinos of various colors, 

 measuring from the eighth of an inch to three inches in thick- 

 ness, but there are no radial lines. (See figure, p. 141.) The 

 people in the vicinity of the quarries where these trunk-like 

 forms are found were much disappointed when told by Dr. 

 Selwyn that they were only concretions. 



On the other hand, many of the fossils found in the Chaz}' 

 and Trenton formations of Ottawa were at one time supposed to 

 be concretions, but are now known to belong to the family of the 

 Monticulipovidce (Micro-Pala3ontology, by Arthur H. Foord, 

 page 24, plate VI.). It is, therefore, important that all such 

 nodular or concretionarj^-looking forms from the auriferous 

 slates of Nova Scotia should be microscopically examined before 

 coming to the conclusion that they are organic remains, and 

 especially before assigning names to what on thorough examina- 

 tion turns out to be of inorganic origin. 



