Speight. — Geological Excursion to Lake Tekapo. 43 



The country is much slipped and the deposit comparatively thin, so 

 that the true relations of the beds are uncertain, and their enumeration is 

 in all probability quite incomplete. This is emphasized by the fact that 

 pebbles of quartz, like those from the quartz drifts of Otago, occur in other 

 parts of the basin, but they were not noticed in the series given above. 



About 200 ft. higher in elevation there is another outlier of uncertain 

 size, consisting of several seams of coal. This has a pitchy lustre, 

 conchoidal fracture, blackish-brown colour, and contains numerous pieces 

 of ambrite. Several of the seams are 2 ft. in thickness, and may be more. 

 They are interstratified with carbonaceous shales, and lie on green sandy 

 clays, which in turn lie on greywacke. The whole thickness of the beds 

 is at least 100 ft., and may be much more, as the surface is masked by 

 debris. The strike is north-east, and the dip north-west about 35°. It 

 was just below this occurrence that the fragment of rock was found 

 showing the sculpture of Monotis. The greywacke here strikes north-west. 



These two patches are evidently the remnants of a much larger deposit 

 which filled a considerable part of the cirque, the great size of which is 

 evidently due to the fact that it was an area of easily eroded beds. The 

 remnant is a very small one, and is rapidly disappearing. This observation 

 is confirmed by the experience of Mr. Pringle, who accompanied us on our 

 visit to the spot and stated that since he last saw it, some twenty years 

 ago, the floor of the basin had completely changed and a great deal of 

 the beds containing coal had disappeared. In the great snow winter of 

 1895 he had packed down half a ton of this coal for use at the Lilybank 

 Station when supplies were short owing to the break in communication, 

 and he said that it burnt excellently. If it were not in such a remote 

 locality no doubt the deposit would have been used up long ago. 



On both sides of the Macaulay between this and the lake are extensive 

 deposits of brownish gravels antedating the glaciation. The pebbles are 

 chiefly greywacke, but quartz is also an occasional constituent, although 

 no quartz-bearing rocks are now found in the locality. These are evidently 

 remnants of a much more widely extended sheet which has been swept 

 away by glaciation. 



In none of these occurrences of Tertiary sediments were any marine 

 fossils found which might definitely prove that the beds themselves were 

 of marine origin. They resemble very closely the deposits described by 

 McKay (1882, p. 62) as occurring in the lower part of the Mackenzie 

 country near Lake Ohau and in the Wharekuri basin, and classified by 

 him as " Pareora," or of Lower Miocene age. As far as the deposits at 

 Wharekuri are concerned, considerable doubt has been thrown on McKay's 

 account by both Park (1905, p. 499) and Marshall (1915, p. 380)— which 

 is unfortunate, seeing that the Wharekuri basin is in the same river-valley 

 as the Mackenzie basin, and the explanation of the origin of one might 

 support that of the other. However, the deposits laid down in the basins 

 of Central Otago, as described by Hutton (1875, p. 64) and Park (1906, 

 pp. 15-19, and 1908, pp. 31-33), arc so similar that a common origin is 

 suggested. Hutton (loc. cit., p. 64) notes the similaiity of the Otago 

 deposits to those at Lake Ohau, and thus incidentally confirms the resem- 

 blance of the Tekapo beds to those of Central Otago. He classifies the 

 latter as of Pliocene age. 



There is thus a possibility that the beds occurring in the Tekapo 

 district are of Pliocene age, though it is possible that the age of the Otago 

 lacustrine (so called) beds has not been definitely determined up te the 

 present, and that this opinion may have to be revised. 



