276 Transactions. 



identification of the breccia as the Hawk's Crag rock could be questioned. 

 Elsewhere actual contacts have not been located, but the complete absence 

 of the Brunner and the Kaiata beds from the Buller Gorge section in itself 

 appears to prove unconformity. McKay in 1895 speaks of the brown-coal 

 series resting on the breccia with some appearance of unconformity,* and 

 at an earlier date describes a probable unconformity in the rocks of the 

 Buller Gorge. | Apparently, however, he supposes that the stratigraphical 

 break is immediately below the brown-coal horizon, and therefore above 

 the conglomerates containing coal pebbles. 



It would seem that the Buller Gorge section in itself proves unconfor- 

 mity between Eocene and Miocene, unless it can be shown that the Hawk's 

 Crag breccia does not belong to the bituminous-coal measures. The peculiar 

 nature of the breccia, however, leaves a loophole for doubt. As already 

 mentioned, it is a slope deposit, and was possibly formed far above sea- 

 leVel, so that the contacts with Miocene rocks at Brighton and in the Buller 

 Gorge may perhaps be cases of overlap rather than indications of true 

 unconformity. 



D. Overlap of Miocene Rocks on the Pre-Tertiary Land-surface. 



In many places the Oamaru rocks of the west coast of the South Island 

 are found to rest on the pre-Tertiary land-surface at points only a short 

 distance from bituminous-coal measures. Thus at Kongahu Point and for 

 some miles southward they rest on granite, at Cape Foulwind and Charles- 

 ton on gneiss, and at Inangahua Junction on greywacke and argillite 

 penetrated by granitic dykes. In Stillwater Creek Valley, at a spot about 

 three miles south of Brunner, is a small outcrop of greywacke surrounded 

 by Miocene rocks. At Kotuku, near Lake Brunner, boring for petroleum 

 has shown that Miocene strata either rest on Aorere rocks or, as previously 

 mentioned, are separated from the latter only by the basal conglomerate 

 of the bituminous-coal measures. 



In the Collingwood district similar overlap of Miocene strata on pre- 

 Tertiary rocks near bituminous-coal measures is found, J and probably the 

 extension of detailed geological surveys through Central Nelson will fur- 

 nish other examples. 



The deposition of Oamaru strata on a pre-Tertiary surface in localities 

 many miles from known outcrops of the bituminous-coal measures may 

 easily be explained as cases of overlap, and therefore it is not necessary 

 to describe such occurrences. Since, however, the marine beds of the 

 Eocene succession are from 1,500 ft. to 3,000 ft. in thickness, the overlap 

 oii Miocene beds on a pre-Tertiary land-surface not far from areas of the 

 bituminous-coal measures is strongly significant. Though in a fault-rent 

 country like New Zealand strong overlaps do not necessarily prove an 

 unconformity, they at least furnish confirmatory evidence of its existence. 



III. The Pre-Eocene Unconformity. 



Owing to the somewhat uncertain age of the Greenland series, the lower 

 time-limit of the unconformity between these supposed Aorere rocks and 



* " Geology of the South-west Part of Nelson and the Northern Part of the West- 

 land District." Mines Report, 1895, Parliamentary paper C.-13, p. 7. 



f " Reports relative to Collections of Fossils made on the West Coast District, 

 South Island." Rep. Geol. Surv. during 1873-74, No. 8, 1877, pp. 103, 104, 105. 



J Park ("The Geology of New Zealand," 1910, pp. 310-11) says that the upper 

 coal-measures conformably follow the bituminous-coal measures, a statement which is, 

 of oourse, opposed to the trend of this paper. 



