272 Transactions. 



B. In one place there is discordance in dip between Miocene and Eocene 

 rocks. 



C. In various localities Miocene strata are in apparently unconformable 

 contact with Eocene strata. 



D. The Miocene rocks exhibit a strong overlap on the pre-Tertiary 

 land-surface. 



A. Water-worn Coal, &c, in Miocene Rocks. 



The chief evidence for unconformity between the Eocene and the Miocene 

 adduced by the writer in 1909 and 1911 consisted in the presence of water- 

 worn coal in the Omotumotu beds near Greymouth. In the valleys of 

 Kaiata and Omotumotu Creeks, over an area of several square miles, are 

 found mudstones, sandstones, and grits containing innumerable grains 

 and lumps of coal.* These rocks were originally discovered by McKay 

 in 1873, and were described by him in the following terms : " Much of the 

 sandstone [loose blocks in a small creek, probably a branch of the Omotu- 

 motu] contained streaks of coaly matter, sometimes as a coal sand, and at 

 other times being rough enough to be called a conglomerate, some pieces 

 thus included being Hin. diameter. I went up the creek, and some dis- 

 tance up found beds of this sandstone, and, in one place, the bed whence 

 this coal conglomerate comes. At this point where I observed it it was not 

 more than 6 in. thick, and the coal pebbles small. I, however, saw blocks 

 in the creek-bed that would prove that this coal conglomerate sometimes 

 reached a thickness of a foot. Other beds of the sandstone became coaly, 

 so as to give it a dark colour and a flaggy appearance, but nowhere, except 

 in the one particular bed, did it approach the conditions of a conglomerate. 

 . . . The coal conglomerate and sandstone beds lie all along the western 

 face of the range to the east of Omotumotu Creek. "f 



In 1900 McKay examined a branch of Kaiata Creek in which coal-seams 

 had been reported to occur, and as a result of his observations stated, 

 " The carbonaceous deposit where examined is about 2 ft. in thickness, 

 and consists of rolled pieces of coal, the largest of which are about 6 in. 

 in diameter, the lesser a fine gravel passing into grit and carbonaceous 

 mud, mixed in varying proportions with arenaceous sands. "% 



In both of the reports quoted McKay regarded the presence of water- 

 worn coal in the Omotumotu beds as proof of unconformity with the 

 bituminous-coal measures. In the earlier report McKay correctly placed 

 the Omotumotu beds below the Cobden limestone, but in 1901 he reversed 

 his opinion as to their relative position, thus avoiding the necessity of 

 having to admit an unconformity in the Cretaceo -tertiary formation .§ 



In the Westport district the lower Miocene beds of two localities contain 

 pebbles of water-worn coal and of carbonaceous shale apparently derived 

 from the bituminous-coal measures. In February, 1911, when traversing 

 Hodge's Creek, a small stream entering the Mokihinui River near Seddon- 

 ville, the writer and Dr. J. Henderson found a few water-worn coaly frag- 

 ments in a sandy mudstone which is probably of estuarine origin, and lies 

 near the base of the Miocene strata as developed in the Mokihinui district. 



* N.Z. Geol. Surv. Bull. No. 13 (n.s.), 1911, pp. 65-66. 



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. 78-79. 



% " Report on Supposed Coal-seams in Kaiata Range, Greymouth." Mines Report, 

 1901, Parliamentary paper C.-10, p. 7. 



§Op cit., p. 8." (See also N.Z. Geol. Surv. Bull. No. 13 (n. a.), 1911, p. 63.) 



