270 



Transactions. 



Art. XXXV. — ■Unconformities in the Stratified Rocks of the West Coast of 



the South Islatid. 



By P. G. Morgan. 



[Bead before the Wellington Philosophical Society, 22nd October, 1913.] 



Introduction. 



The area in which occur the unconformities described in this paper lies 

 to the westward of the Southern Alps, and is in shape a drawn-out triangle 

 having its base to the north and its extremely acute apex to the south. 

 Both by reason of its physical isolation and because of other peculiarities 

 this region forms a geological unit, the history of which may to some extent 

 be considered separately from that of other parts of New Zealand. Since 

 only a comparatively small portion of the area has been surveyed in de- 

 tail, no complete statement regarding the unconformities that occur in the 

 stratigraphical succession can yet be made, and the present account is 

 confined to those that have been observed during the geological surveys 

 of the Westport district and of that part of North Westland which lies 

 to the west of the Southern Alps. 



The order of succession in the sedimentary rocks of these districts is 

 shown by the following table : — 



Unconformity. 



Moutere Gravels 

 Oamaru series . . 



/Upper — Blue Bottom, &c. 

 ! M - lrll f Cobden Limestone 

 1 imaaie \ Port Elizabeth beds 

 I Lower — Omotumotu beds 



Pliocene. 

 Miocene. 



Unconformity. 



Bituminous-coal measures 

 (Mawheranui or Waima- 

 ngaroa series) 



Kaiata beds (including Island \ 



Sandstone) 

 Brunner beds . . . . } 



Paparoa beds ; Hawk's Crag 



and Brighton breccias 



Eocene. 



Great Unconformity. 



Aorere (Greenland) series 



Ordovician.* 



* The Greenland series of New Zealand Geological Survey Bulletins Nos. 6 and 13 is 

 here provisionally correlated with the Aorere series of Bulletins Nos. 3 and 11. Decisive 

 proof of this correlation has not been obtained, but the age of the rocks in question does 

 not materially affect any statement in this paper. 



