Andrew. — On the Clarendon Phosphate- deposits. 461 

 The results of analyses of the basalt are as follows : — 



1. From Stony Knob. 2. From Stony Knob : S.G. =2"957. 3. From 

 Stony Knob. 4. Average of 1, 2, and 3. 5. Cemetery Hill : sum of results 

 of the last table. (Only one estimation of Ti0 2 was made.) 



These results show that the basalt is 2 or 3 per cent, poorer 

 in CaO than a normal basalt, but otherwise it coincides fairly 

 closely with standard analyses, such as those given by Rosen- 

 busch.* 



Age of the Basalt. — Captain Huttonf considers that toward 

 the end of his Oamaru formation great volcanic activity took 

 place in the neighbourhood of Dunedin, resulting in the basalts 

 at, inter alia, "the head and both sides of Waihola Lake." This 

 flow is connected with the basalt-flow at Clarendon, and we may 

 consider the latter as belonging to the close of the Oamaru for- 

 mation, and thus either Upper Eocene or Oligocene. There is 

 no evidence in this district to show what interval of time elapsed 

 between the deposition of the calcareous series and the extrusion 

 of the basaltic flow. Captain Hutton does not give the evidence 

 on which he bases his opinion of the age of the eruptive rocks 

 round Dunedin ; he does, however, show that the volcanic ac- 

 tivity at Oamaru was of this age. Professor Park mentions that 

 the basalt rests on the mica-schist, and on different members of 

 the Oamaru formation, which was elevated and denuded prior 

 to the emission of the flow. For this reason he places the erup- 

 tion of the basalt in the Upper Miocene or Pliocene. 



* Rosenbusch, " Elemente der Gesteinlehre," p. 322 

 t Hutton, " Geology of Otago " (1875), p. 56. 



