REPORT OF THE CHIEF ASTRONOMER 

 SESSIONAL PAPER No. 25a 



481 



total at least 30,000 feet in thickness. This is a minimum estimate, for the 

 field sections as plotted show a total thickness of over 40,000 feet. The chief 

 uncertainty resides in the determinations for the top and bottom members. 

 As noted in the columnar section their respective strengths, namely, 3,000 and 

 10,000 feet, are estimated as the lowest possible minima. (Figure 34). 

 The whole succession is shown in the following table : — 



Columnar section, Pasayten series. 



Member. 



Thickness in 

 feet. 



Lithological Character. 



L. 



K. 



J. 

 I. 

 H. 



G. 

 F. 

 E. 

 D. 

 C. 

 B. 



A. 



3,000 



7,100 



1,400 



300 



3,500 



200 

 1,500 



100 

 1,100 



600 

 10,000 



1,400 



Top, erosion surface. 



Gray to black argillite, bearing plant-stems and impressions of ammonite 



shells. 

 Gray and green feldspathic sandstones with interbeds of black argillite 



and thin lenses of conglomerate ; fossil plants and animal remains. 

 Coarse conglomerate. 

 Black argillite. 

 Green feldspathic sandstone with rare argillitic interbeds ; fossil plants 



and shells about 200 feet from the top. 

 Fairly coarse conglomerate. 

 Gray and green, feldspathic sandstones. 

 Conglomerate. 



Gray and green, feldspathic sandstone. 

 Red argillite and sandstone. 

 Very massive, medium-grained arkose sandstone ; fossil plants at about 



900 feet from the top and also about 3,500 feet from the base. 

 Volcanic agglomerate conformable to sandstone B. 





30,200 



Base, unconformable contact with older Remmel batholith. 



The volcanic agglomerate was crossed in four different traverses. Sufficient 

 information was obtained to indicate its relations to the neighbouring forma- 

 tions. The agglomerate forms a remarkably straight and clearly continuous 

 band of nearly even width, crossing the whole five-mile belt in a northwesterly 

 direction and thus parallel to the strike of the adjacent sandstone. Though the 

 breccia at every observed outcrop is quite devoid of bedding-planes, there can be 

 little doubt that it is everywhere conformably underlying the sandstone. It is 

 regarded as practically contemporaneous with the lowest beds of member B. 

 Within the Boundary belt the agglomerate rests on the eroded surface of the 

 Remmel batholith. The petrographic character of the agglomerate will be 

 described in a special section of this chapter. 



For a distance from the agglomerate the granodiorite is thoroughly decolour- 

 ized and has the look of having undergone secular disintegration before the 

 breccia was deposited. The depth of this shell of ancient weathering was 

 measured near the Pasayten river and found to be about 400 feet. Such a depth 

 means that the pre-volcanic surface was characterized by low slopes on which 

 the rotted rock could lie and slowly increase at the expense of the fresh grano- 

 diorite beneath. The straightness of the line showing the contact between 



25a— vol. ii— 31 



