LOWER CAMBRIAN TERRANE 327 



with a dip of 60° N. If these beds continue down the brook 

 they must cgme directly in contact with the central portion of 

 the Protolenus beds of the St. John terrane. 



The strikes and dips mentioned are shown in the accompany- 

 ing diagrammatic sketch, Fig. 11. They illustrate the irregu- 

 larities occurring within the St. John quartzite at the base of the 

 Middle Cambrian and the fact that the supposed unconformity 

 at the base of the St. John quartzite is a break or split within 

 that formation and not below it. There does not appear to be 

 any evidence for a safe conclusion that there is an unconformity 

 between the Lower Cambrian Hanford formation and the Middle 

 Cambrian St. John quartzite. 



City of St. John. — At the head of Seely street, beside the 

 Park road, in the city of St. John, the pre-Cambrian (Algon- 

 kian) rocks have an uneven surface where the basal beds of the 

 Hanford formation rest against them with a strongly marked 

 unconformity. Passing up through about 150 feet of thickness 

 of the * Etcheminian ' Hanford terrane, we find the basal bed 

 of the St. John quartzite resting conformably on the shales and 

 thin-bedded sandstones of the Hanford terrane. There is no 

 evidence whatever of any unconformity at this point. 



Catons Island. — I also examined the contact of the two 

 formations on the east side of Catons Island, Long Reach. 

 Here the purplish-colored sandstones are conformable in strike 

 and dip with the St. John quartzite. 



Conclusions. — The presence of a quartzitic sandstone of the 

 character of the St. John quartzite is not in itself proof of any 

 decided unconformity. It indicates a decided change in sedi- 

 mentation and the derivation of material from some other source 

 of supply, but such a phenomenon may occur in the midst of a 

 terrane where the fauna is the same above and below the quartz- 

 ite. This is well illustrated in the Eureka district of Nevada, 

 where the Eureka quartzite, 300 feet in thickness, occurs in mid- 

 Trenton, the limestones below and the limestones above the 

 quartzite carrying the same species of the Trenton fauna. 



Judging from the character of the St. John quartzite as I have 

 seen it, and the description given of it at other localities by Mr. 

 Matthew, I think that the sand of which it is formed came 



