371 







Thickness. 





Feet. 



Metres. 



Lower Ordovician. 



Bretonian. 



700 



213 



Cambrian. 



Johannian. 

 Acadian. 



750 

 200 



228 

 61 



Basal Cambrian. 



Etcheminian. 



1 ,200 



365 





Coldbrookian. 



? 



? 



The Acadian, Johannian and Bretonian together compose 

 the St. John group which consists largely of dark slates and 

 very fine sandstones. Fossiliferous beds occur at many 

 horizons. 



The Etcheminian strata are shales, sandstones and 

 conglomerates and fossils are not common in them. The 

 Coldbrookian consists of various types of volcanic rocks. 



Dr. Matthew regards the St. John group as being the 

 equivalent of the whole of the Cambrian proper including 

 the Lower Cambrian, Olenellus zone or its equivalent, and 

 a part of the lower Ordovician. The Etcheminian, because 

 in certain places it seems stratigraphically unconformable 

 to the overlying Acadian and because it varies widely in 

 thickness from place to place, is thought by Dr. Matthew 

 to unconformably underlie the Cambrian proper. The 

 Etcheminian is stated to contain a fauna of Cambrian 

 aspect but of an earlier type than that customarily classed 

 in other regions with the Olenellus zone. The Cold- 

 brookian is described by the same author as formed of 

 35063— II ^A 



