140 T7-ansactions. 



in many of the creeks, and forms prominent escarpments on the banks 

 of many of the larger streams. The Maruwenua River, a north-easterly- 

 flowing tributary of the Waitaki, rising in the neighbourhood of Dansey's 

 Pass, where a distant sag is noticeable in the main Kakanui-Kurow Range, 

 is flanked by the rather steeply sloping back of a tilted block, the stripped 

 surface of which dips beneath the Tertiaries exposed in the neighbourhood 

 of the river. 



The Waitaki River flows in an east-south-east direction near the base 

 of the well-preserved fault-scarp of the South Canterbury block mountains. 



The Tertiary rocks in the Waitaki Valley occur ' in an elongated 

 depression between the mountain-ranges of North Otago and South Canter- 

 bury, and the origin of this depression has been referred to various' causes. 

 Haast had no difficulty in imagining that a glacier was the agent of 

 erosion ; Hutton and Park invoked the aid of a pre-Tertiary river, the 

 valley of which, after general subsidence of the land, was drowned by the 

 encroachment of the sea, and the sedimentary deposits laid down. Marshall 

 detected signs of tectonic movement in the neighbourhood of Wharekuri, 

 and Cotton later elaborated the idea in his work on the block mountains 

 of Otago, and described the dej^ression as a somewhat complex graben 

 between the uplifted block mountains of North Otago and Canterbury. 



The Tertiary rocks consist of quartz conglomerates and sands, and 

 sometimes fireclays, with seams of inferior brown coal. These rocks rest 

 on the eroded surface of the older greywacke rock, and are followed by 

 greensands, often pebbly, sandy, and micaceous, and containing marine 

 fossils 20 ft. above the coal. These greensands pass up into more 

 calcareous greensands, containing much less quaitz and mica, but glau- 

 conitic casts of Foraminifera are abundant. The limestone which overlies 

 these greensands sometimes has at its immediate base a band of calcareous 

 greensand containing brachiopods in abundance ; in other cases the 

 transition from a calcareous glauconitic sand to a slightly glauconitic 

 limestone is almost insensible. The glauconitic limestone passes up into 

 a much harder limestone free from giauconite, and the latter rock is capped 

 by very fossiliferous concretionary hardened bands, covered in turn by 

 more sandy beds, which appear to be unfossiliferous in their upper part. 

 Overlying these rocks unconformably is a heavy deposit of river-gravel 

 and silts. 



III. Historical Summary. 



That the historical summary of the views of previous workers may be 

 more easily followed, the classification as finally adopted by McKay for the 

 Waitaki Valley is tabulated. 



