Uttlet. — Tertiary Geology, Wharekuri to Otiake River. 167 



a difficult matter to trace their boundaries, and this has not been attempted 

 in the present paper. The angular gravels are ascribed by McKay to the 

 action of glaciers — that is, they are glacier-deposits that owe their origin 

 to former glaciers from the neighbouring Kurow and Hakataramea Moun- 

 tains. Not having discovered these Triassic and Permian fossiliferons rocks 

 in the Kurow Mountains, McKay concluded that glaciers brought them 

 from the Canterbury mountains which were known to contain these older 

 fossiliferons rocks. There is, however, a total absence of the character- 

 istics of glacial deposits, glacial striations being 'quite lacking. It is true 

 that large masses of rock and fine silts and clays are mixed confusedly 

 together in the deposits near Wharekuri. Marshall explained these angular 

 deposits differently, and (1915, p. 381) stated that the Maitai rocks in the 

 neighbourhood of the fault (Wharekuri-Otekaike fault) have been much 

 shattered ; that weathering has developed their shattered nature, and 

 they break down into " a clayey material which still contains angular 

 fragments of rock." Park (1904, p. 448) traced the fossiliferons boulders 

 to their source near the summit of Mount Mary. The rocks were found, 

 in situ at a height of 5,160 ft., at a point distant about three miles and 

 a half from the Wharekuri-Otekaike fault-line. These deposits which 

 occur close to this hne were probably derived from the dissection of the 

 fault-scarp as it rose, for deep aggradation would take place as the deform- 

 ation proceeded. The sloping surface of the tilted block, to the west of 

 the fault-line, would also undergo degradation by the numerous consequent 

 streams, and the waste would be spread out on the floor of the depression, 

 forming an alluvial gravel-plain. This plain appears to have been built 

 up after the reduction of the valley lowland to somewhat low relief. The 

 extensive aggradation would therefore imply a great increase in the supply 

 of waste due to the increasing differential elevation. As the streams 

 that deposited these gravels are now well entrenched, regional uplift has 

 probably been the most recent movement. McKay believed that the 

 tilted sandstone gravels at Wharekuri lay conformably above the higher 

 fossiliferons beds. They may do so, but the writer was unable to satisfy 

 himself on that point. Theie is no doubt, however, that they have been 

 involved in the differential movements, and may possibly represent the 

 period of emergence of the land. 



VII. SUMMAEY AND CONCLUSION. 



(1.) The Maruwenua limestone is overlain directly by the Otiake beds 

 (Hutchinsonian-Awamoan). 



(2.) McKay's unconformity between the lower and upper parts of the 

 limestone is non-existent, and all other observers agree that the rock is a 

 unit. 



(3.) McKay correlated the base of the limestone with the Ototaran 

 limestone ; the upper part (his Otekaike limestone) must therefore be 

 Upper Ototaran, and the overlying beds (McKay's Hutchinson's Quarry 

 beds) are the equivalent of the Hutchinsonian-Awamoan of the coastal 

 district. ^ 



(4.) The upper part of the limestone at Landon Creek contains a number 

 of brachiopods that are similar to the brachiopods from the lower portions 

 of the Maruwenua limestone (so-called Waitaki stone). Some of these 

 brachiopods do not rise above the Ototaran of the typical Oamaru district. 

 The evidence points to the limestone of the Waitaki Valley being Ototaran. 



