HuTTON, — Geology of North-eastern Otago. 429 



45°, reach the Otepopo Kiver, and their relation to the bhie 

 clay in Allday Bay cannot be ascertained ; but to the south a 

 series of dark-green soft sandstones, weathering reddish-brown, 

 dipping 25° W., and underlain by blue clay, are apparently 

 interstratified with tachylyte tuffs. I could find no fossils 

 in these rocks ; and, unfortunately, they are separated from 

 the Onekakara clay by a mass of silt and gravel, so that 

 here also their relations are not quite certain, although I 

 saw no reason to doubt their identity with the Onekakara 

 clay. One tachjdyte which I collected is a compact, dull, 

 earthy, black rock, and looks like a dark clay ; it breaks up 

 irregularly into small fragments, generally with curved surfaces 

 (S.G-.=2-14) It is minutely cracked in all directions, is not vesi- 

 cular, and of a clear olive-brown, in places paler with globulites, 

 sometimes scattered, sometimes collected into irregular but 

 sharply defined patches, generally angular, but often in lines. 

 Other parts are darker, with abundant globulites. There are 

 no microliths. Another specimen was dark blue-black, with a 

 crystalline texture, and rounded black globules among the 

 crystals (S.G.=^2-38). Under the microscope this is seen to be 

 a tuff, made up of fragments of a brownish-yellow vesicular 

 tachylyte in a crystalline calcareous cement. The vesicles 

 are elongated in the same direction, but there is no other 

 fluxion structure. These tachylyte rocks resemble those from 

 Waireka Valley and White- water Creek in the Trelissick Basin, 

 all of which belong to the Oamaru System. Whether they 

 are or are not of the same age must remain for the present an 

 open question. Their peculiar structure is probably due to lava 

 streams, which have run rapidly into water and have been 

 shattered mto minute fragments. 



Conclusion. 



In a paper read before the Geological Society of London, 

 in June, 1885,''= I have taken it for granted that the Hutchinson's 

 Quarry beds formed part of the upper eocene, or Oamaru 

 System ; and that the volcanic outbursts at Oamaru were 

 contemporaneous with them. This was my former view, but I 

 know now that I was wrong in one, and perhaps in both, of 

 these points. The alterations, however, do not affect in any 

 way the general drift of that paper, which is to show that the 

 fossils of the upper part of the cretaceo-tertiary and of the upper 

 eocene formations of the Geological Survey are identical, and 

 that there is no stratigraphical brealc between them — i.e., 

 between the Curiosity Shop beds and the Otakaika limestone as 

 representing the upper eocene, and the Ototara and Maerewhenua 

 limestones as representing the cretaceo-tertiary. My repudia- 



* " Quar. Jour. Geol. Soc. of Lond.," vol. xli, p. 647. 



