APPLICATION OP PRINCIPLE OF TRANSGRESSIVE OVERLAP 573 



of division between it (the Saint John group) and the Huronian (Algonkian) 

 is marked by conglomerates of mechanical origin which show no trace of the 

 hardening process by which the Huronian conglomerates and breccias have 

 been so firmly cemented."* 



The Acadian represents the lower part of the Middle Cambric and 

 begins with the Saint John quartzite, which is succeeded by the Pro- 

 tolenus zone, and this in turn by the Paradoxides zone. Beneath the 

 Saint John quartzite is a series of red and green sandy shales 150 feet 

 thick, below which lies the red basal conglomerate. Both the red shales 

 and the conglomerate are referred to the Etcheminian or pre-Saint John 

 terrane. This terrane is fully developed at Hanford Brook, Saint Mar- 

 tins, some 30 miles north of east of Saint John, where it is 1,200 feet 

 thick. Here it begins with a coarse purplish red conglomerate 60 feet 

 thick, which rests upon amygdaloidal greenstones of an older (Cold- 

 Brookian) series, and passes upward into sandstones and flags some 300 

 feet thick, followed by a second conglomerate 35 feet thick, which in 

 turn is followed by shales and sandy shales to the top of the series. 



It is evident, then, that we have here an overlapping series, with a 

 basal conglomerate in each case, that of the Saint John region, however, 

 being equivalent, not to the basal bed of the Etcheminian series of the 

 Hanford Brook section, but to the shales of the upper division of that 

 series. 



In Cape Breton island the Lower Cambric or Etcheminian strata were 

 found by Matthew to have a thickness of 3,000 to 5,200 feet at Mira 

 bay, on the eastern coast. Twenty miles farther west, on East bay (Bras 

 d'Or lakes), only 500 feet of Etcheminian occurs. Both sections show 

 a basal conglomerate resting on older rocks, succeeded in both cases by 

 Middle Cambric strata, at the base of which an erosion interval is indi- 

 cated in some other sections. 



On the East Bengal road the lower Etcheminian is 3,200 feet thick, 

 decreasing on the West Bengal road to 1,300 feet, and to 270 feet at 

 Dugald brook, on East bay. The upper division likewise increases from 

 2,000 feet on the East Bengal to 1,700 feet on the West Bengal road, 

 and to 230 feet at Dugald brook. The increase of the lower beds west- 

 ward appears to be due to progressive overlap of the beds, while the 

 greater thickness of the upper beds in the eastern section, when taken 

 in connection with the heavy conglomerate which lies at the top of the 

 series in the west, seems to suggest retreatal features of the type more 

 fully discussed later on. Of course here, as in all the sections of dis- 

 turbed areas, the possibility of the existence of faults and folds must be 



* Matthew : Fauna of Saint John group, pt. 1, 1882. p. 87. 



