392 Transactions. — Geology. 



do not now propose to do so, but shall refer these rocks to my 

 Mataura series, which is the same as Hutton's Mataura series 

 of 1899.- 



HoKONui System — Huttonj (Syk., Eangitata System — 



Pabk). 



The vast assemblage of sedimentary strata just described 

 comprises wholly, or in part, the Mount Torlesse formation of 

 Von Haast. The rocks, unfortunately, in Mount Torlesse 

 contain none of the fossiliferous horizons present in Nelson, 

 upper Eangitata, or Nugget Point, with the exception of some 

 indistinct plant-remains and a calcareous flattened tubular 

 body which has been doubtfully referred to an annelid. In 

 the absence of shell beds it is impossible to fix the posi- 

 tion of the plant and annelid beds in relation to known hori- 

 zons elsewhere. The Mount Torlesse plant beds may be con- 

 temporary with the Mount Potts plant beds, but in the ab- 

 sence of satisfactory evidence this correlation may be called 

 in question at any time. 



The Mount Torlesse formation, according to Yon Haast, 

 has a thickness of at least 25,000 h. I It was placed by him 

 up till 1865 in the Silurian period, but in 1878 he referred 

 it to a time ranging from Paleozoic to Lower Mesozoic.§ The 

 Carboniferous age of the lower beds was apparently based on 

 the supposed identification of Orthis, Productus, and other 

 Palaeozoic genera in the Mount Potts Sj)iriferina beds at 

 Rocky Gully. II 



The assemblage of strata exposed in the uj^per Eangitata 

 attains a thickness not less than 40,000 ft. It possesses, too, 

 well-marked fossiliferous groups of beds which are absent in 

 the Mount Torlesse district. I am therefore reluctantly com- 

 pelled to set aside Von Haast's formation-name, chiefly for 

 the reason that the strata at Mount Torlesse do not afford the 

 data necessary for their subdivision into groups and series of 

 beds. 



The main object of my investigations in the past three 

 years has been to determine the succession and stratigraphical 



* Hiitton, Trans. N.Z. Inst., 1899, vol. xxxii., p. 183. 



t When I placed this paper before the Institute I included the 

 Mataura, Shaw's Bay, and Kaihiku .series in my Eangitata syscem. The 

 name Rangitata seemed to me at that time to be more suitable than 

 either the name IMount Torlesse or Ilokonui ; but on further considera- 

 tion I have decided to adopt Captain Hutton's name Hokonui, using it 

 in a somewhat more extended sense than originally intended by its 

 author. The Hokonui system will now include all the rocks that are 

 fctraligraphically connected from the I'ermian to the Jurassic. 



I Haast, "ijeology of Canterbury and Westland," 1879, p. 279. 

 § L.c, p. 279. 



II L.c, p. 272. 



