30 The N.Z. Journal of Science and Technology [Feb. 
Zealand, and, as a matter of fact, it lias been observed by me in the 
St. Bathan’s district. The quartz drifts, with associated clays and 
lignite seams, are several hundred feet thick at St. Bathan’s, but at the 
Vinegar Hill claim, three miles to the south-west, the “ wash ” is only 
a few feet thick. On the higher slopes of the hill it apparently thinned 
out altogether, but westward, in the present face of the Vinegar Hill 
claim, 14 ft. or more of quartz drift may be seen, overlain by 70 ft. or 
80 ft. of green claystone. 
In tentatively assigning portions of the Cencral Otago Notocene beds 
to the highest Oamarnian and even to a post-Oamaruian stage Dr. Cotton 
could have quoted Professor Park, who places his Manuherikia Series in 
the Pliocene, and mentions Hector and Hutton as his authorities (1906, 
p. 16). Strangely enough, however, Park fails to quote McKay, whose 
authority in this particular instance must be regarded as weighty, for he 
was far better acquainted with Central Otago than Hector or Hutton. 
Moreover, Hector apparently acquiesced in McKay’s views, which, roughly, 
were that the Notocene beds are of two quite different ages—Miocene and 
Cretaceo-Tertiary. There can be no doubt that McKay was driven to this 
conclusion by the supposed necessity of upholding the Cretaceo-Tertiary 
hypothesis of the old Geological Survey at all costs. But for the hampering 
influence of this hypothesis it is quite evident that he would have correlated 
all the lignites of Central Otago, and the accompanying quartz conglome¬ 
rates or drifts, with the Ngaparan stage of the Oamaruian. This appears 
to me to be a nearly correct view. Doubtless it ought to be modified in 
the direction indicated by Dr. Cotton, but not to the same extent so far 
as the quartz drifts are concerned. McKay, though not overclear in his 
method of presentation, evidently had the question of overlap more or less 
in his mind. The quartz drifts of the Ngaparan stage and those of Central 
Otago may be regarded as belonging to practically one stratum, formed 
during a period of land-depression. The difference in age between the 
inland and the seaward portions probably corresponds rather to the 
time difference between the Ngaparan and Waiarekan stages than to 
that between the Ngaparan and Pareoran stages, as Dr. Cotton seems to 
suppose. The total overlap of the Notocene beds, however, may well 
correspond to the whole of the Oamaruian ; but, since there is no known 
occurrence of the marine Wanganuian stages in the south of New Zea¬ 
land, I see no reason for supposing that the- overlap extended to the 
Wanganuian. The Maori Bottom gravels, which are probably Pliocene, 
and therefore correspond to some part of the Wanganuian, are, as 
already stated, believed to be unconformable to the St. Bathan’s Series, 
so that they need not be considered! in connection with the Oamaruian 
overlap. 
Dr. Marshall’s views regarding the age of the Central Otago Notocene 
beds may also be cited. A few years ago he considered the “ lake- 
basin ” beds to be of Wanganuian age (1912, p. 46), but quite recently 
he has stated that the quartz grits of the Lawrence district are at 
the latest of very early Tertiary age (1918, p. 63). In the present state 
of our knowledge one can hardly avoid tentatively correlating the 
Tuapeka quartz grits with those of other parts of Central Otago, 
and, since the former are certainly of Miocene or pre-Miocene age, the 
St. Bathan’s Series cannot be regarded as much, if any, younger than 
Early Miocene. 
