.Morgan. — Unconformities in Stratified Rocks of West Coast. 273 



Again, in the Lower Buller Valley for some miles eastward from Hawk's 

 Crag, the conglomerates, grits, and sandstones of the lowest Miocene 

 horizon contain numerous pebbles and grains of coal and carbonaceous 

 shale. In places carbonized fragments of wood, some of which are more 

 or less rounded, are present, so that caution is necessary in considering 

 the origin of individual pieces of coal-like material. There need, however, 

 be no doubt but that the pebbles of carbonaceous shale and most of the 

 coaly fragments are derived from coal-bearing strata, and, unless evidence 

 to the contrary can be obtained, the natural conclusion is that the bituminous- 

 coal measures are the source. 



The following analyses show the composition of the fragmental coal 

 in the Miocene rocks :■ — 



I and 2. Omutumotu Ridge. Samples collected by Geological Survey (probably by 

 A. McKay in December, 1873). Analyses by W. Skey (Lab. Rep. No. 10, 1875, 

 pp. 9-10)! 



3. Upper part of Kaiata Creek. 



4 and 5. Hodge's Creek. Bright coal and impure coal. 



6. Pebbles in conglomerate, close to Blackwater Bridge, Buller Gorge Road. 



(Analyses 3-6 by Dr. J. S. Maclaurin and staff, Dominion Laboratory.) 



From these analyses it appears that the samples, with the exception 

 of that from the Buller Gorge, have a fairly uniform composition. Volatile 

 matter predominates over fixed carbon, and moisture in the purer material 

 averages a little over 7 per cent. The pebbles from Blackwater Bridge 

 consisted of very impure material, and were taken from porous conglomerate, 

 so that weathering may be wholly or in part the cause of the low volatile 

 content. Unfortunately, no other sample from the Buller Gorge has been 

 analysed, and therefore it is not certain that the analysis given is fairly 

 representative of the fragmental coal in that locality. 



There are Eocene coal-seams in the Greymouth district similar in com- 

 position to samples 1-4, and the more altered portions of the Miocene coal- 

 seams in the Inangahua district also exhibit some resemblance. The latter, 

 however, cannot have been the source of the carbonaceous fragments in 

 the Buller Gorge conglomerates, which are, without much doubt, in a lower 

 horizon. To this statement the thin seams near Hawk's Crag are an ex- 

 ception, since they occur interbedded with the coal-pebble conglomerates. 



In general the Oamaru coal-seams are much higher in water than the 

 carbonaceous fragments, and this furnishes another reason why the latter 

 are not likely to have been derived from the former. On the other hand, 

 at the beginning of the Miocene period the Eocene coal-seams had been in 

 existence for a long time, and, according to the writer's belief, had been 

 uplifted or otherwise associated with earth-movements, so that their 



