154 Transactions. 



Art. XXIII. — Tertiary Geology of the Area between Wharekuri and the 



Otiake River, North Otago. 



By G. H. Uttley, M.A., M.Sc, F.G.S., Scots College, Wellington. 



[Bead before the Wellington Philosophical Society, 10th December, 1919 ; received by Editor, 

 Slat December, 1919 : issued separately, 15th June, 1920. 



Contents. 



I. Introduction. 

 II. General Description of the Area. 



III. Geology of the Area. ^ 



(1.) Wharekuri Basin. 



(2.) Awahokomo Basin. 



(3.) Awakino Basin. 



(4.) Kurow River to Otiake River. 



IV. General Succession and Palaeontological Notes on the Tertiary Rocks. 

 V. General Remarks on the Physiography. 



(1.) Kurow Block. 

 (2.) Awakino and Trig. G Blocks. 

 VI. The Gravels. 

 VII. Conclusion. 



I. Introduction 



The area described in this paper covers a narrow strip of country on the 

 right bank of the Waitaki River, extending from Wharekuri Creek to the 

 Otiake River. The adjacent strip of country south of the Otiake River 

 has already been described in another paper in this volume. Although 

 the exposures of Tertiary rocks are few and widely distant, being obscured 

 over the greater part of the area by heavy gravel deposits, the general 

 sequence of the beds" is clear. McKay has dealt with the country in som,e 

 detail, but various modifications of his interpretation of the succession 

 are necessary. The writer's thanks are due to Mr. P. G. Morgan, Director 

 of the New Zealand Geological Survey, for permission to examine the lists 

 of fossils collected by McKay, and determined by the late Mr. Henry Suter. 

 An examination of these lists serves to emphasize the truth of the writer's 

 contention (refer to Thomson, 1915, p. 123) that the molluscan fauna below 

 the limestone is similar to that above the limestone. The upper beds, 

 however, contain a much greater number of species. 



A full historical account of previous geological work in the Waitaki 

 Valley has already been given in another paper in this volume (pp. 140-143), 

 and only a brief critical summary of the views of other writers is necessary 

 here. 



McKay's opinion that there is an unconformity in the Tertiary rocks 

 at Wharekuri, and that the coal occurs at the top of the sequence, is 

 untenable. McKay was right in his view that an horizon of fossiliferous 

 beds occurs above the limestone at Wharekuri, and that they are at the 

 Hutchinson Quarry horizon. These beds are the equivalent of the writer's 

 Otiake beds (Hutchinsonian-Awamoan) at Otiake, Otekaike, and Duntroon. 

 As the base of the limestone is not exposed at Wharekuri, Otiake, or 

 Otekaike, McKa}' was right in not correlating the limestone exposed in 

 these places with the basal part of the Maruwenvia limestone, but with 

 a higher part of that rock. The " Pareoran " characteristics of the fauna 

 below the limestone at Wharekuri caused Park (1905, p. 527) to correlate 



