Uttlby. — Tertiary Geology, Wharekuri to Otiake River. 165 



done by Park in his latest work (1918, p. 26). Many of the species con- 

 tained in these lower greensands occur also in the Awamoan, but the 

 latter horizon contains a much greater variety of species, and a large 

 number of these appear to be restricted to" this horizon. In the Oamaru 

 district the brachiopods have proved serviceable in differentiating several 

 horizons, but some of these brachiopods are apparently restricted to this 

 area, and detaijed correlation with beds in the Waitaki Valley is not yet 

 possible. This brachiopod fauna has been discussed in another paper in 

 this volume (pp. 152-53). Corals, Echinoderms, and Foraminifera occur 

 abundantly in the Oamaruian of North Otago, but our knowledge of 

 them is very incomplete, and useless for detailed stratigraphical work. 

 A revision of all these groups is urgently needed. 



Of the ninety-four species of Mollusca determined from the beds above 

 the limestone in the Waitaki Valley (Otiake beds), seventy-three species 

 occur in the typical Awamoan at Oamaru, four occur in the Hutchinsonian 

 (of Thomson), twelve forms have apparently not been recorded elsewhere 

 in North Otago, whilst only five species have not been previously recorded 

 from post-Ototaran beds. Five of these not recorded elsewhere are new 

 species, seventy-nine species have now been listed from the greensands 

 below the limestone in the Waitaki Valley, and fifty-six of these occur in 

 the Awamoan beds at Oamaru. Nearly three hundred species have been 

 recorded from the Awamoan beds at Oamaru ; but in the case of the beds 

 of the Waitaki Valley the collections are few, and previously unrecorded 

 species are continually turning up. The figures quoted above, in the 

 absence of fairly exhaustive collections, do not give much ground for 

 definite conclusions, but they do show that the Otiake beds contain a 

 moUuscan fauna of which 78 per cent, occurs in the typical Awamoan 

 beds of Oamaru. Tl^e faunk of the greensands below the limestone con- 

 tains 70 per cent, of the fossils recorded from the Awamoan at Oamaru, 

 showing that in the Waitaki Valley the fauna above and below the 

 limestone has a strong resemblance to the typical Awamoan fauna (Hutton's 

 Pareora). 



V. Physiography of the Area. 



« 



(1.) Kurow Block. 



From what has already been said it will be evident that Cotton's 

 statement (1917a, p. 285) that the Waitaki River " follows a complex 

 graben along the northern block-complex . . . which forms the 

 northern highland of Otago " is amply justified by the geological evidence. 

 This graben is bounded on the south-west . by the elevated block called 

 the Kurow - Mount Mary Range (Kurow block) ; on the north-east it is 

 flanked by the block mountains of South Canterbury ; .on the south-east 

 by a portion of the Kakanui block {loc. cit., p. 272). Towards the north- 

 west the fault on the Canterbury side of the river and the Wharekuri- 

 Otekaike fault approach each other, and probably coalesce farther up the 

 Waitaki Valley ; but this area lies beyond the scope of the present paper. 



The Kurow - Mount Mary Range is an elevated tilted block of probably 

 complex structure ; it is elongated in a north-westerly direction. It is 

 bounded towards the west by a conspicuous fault-scarp (loc. cit., p. 278), 

 and its rather steeply dipping back slope descends towards the Waitaki 

 River, and is then intersected by the Wharekuri-Otekaike fault. A line 

 of dislocation runs from the Otekaike River to Dansey's Pass to meet the 

 great re-entrant occupied by part of the Maniototo depression (loc. cit., 



