FiNLAYSON. — Geology of the Reefton Gold-veins. 



87 



The belt of quartz veins runs through them in a north-and -south direction 

 along their strike. 



Erosion along an anticline in the slates has exposed beneath them in places 

 a series of cherts, slates, and limestones containing fossils of Devonian age. 



As regards the relations of these three formations, the granites on both 

 sides are intrusive into the slates, as seen by the intense local contact-effects 

 in Larry's Creek and elsewhere, and to their intrusion is doubtless due the 

 intense folding and crushing of the included belt of slates. These latter 

 are claimed by Hector and McKay to rest with pronounced unconformity 

 on the Devonian rocks,* and from other considerations this is probably 

 the case, but good sections showing the junction between the two forma- 

 tions are difficult to obtain owing to the faulting and disturbance that the 

 rocks have undergone. McKay has described in some detail the Devonian 

 sequence exposed in the Inangahua Gorge, Lankey's Gully, Waitahu River, 

 and Rainy Creek.t North and south of these limits the Devonian rocks 

 have not been recorded. 



Next in age comes the early or middle Tertiary series of coal-bearing 

 rocks, well developed at Boatman's and at the head of Murray Creek. In 

 these localities good seams of high-grade bituminous coal occur, from which 

 over 100,000 tons of coal has been won. This coal is a valuable asset to 

 the district, and is in high favour for household purposes. Accompanying 

 the coal-bearing rocks are auriferous gravels and cements (which have 

 been worked in places), sandstones, and, further north, limestones. The 

 base of the series is occupied by coarse greywacke breccias, well exposed in 

 the BuUer Gorge, on the east flanks of the Paparoa Range. The rock series 

 thus described as exposed in the Reefton district is typical of the great 

 coal-bearing series of the West Coast, whose age is still a matter of doubt. 

 They have been classed by Hector and McKay as Cretaceo-tertiary,J but 

 the Hmestone fossils indicate a much younger age. Whatever their age, 

 they rest with marked discordance on the older rocks, and are also deeply 

 involved in the 'structure of the ranges on which they occur, as is well seen 

 in Murray Creek. 



The Inangahua Valley is occupied by gravel terraces of Pliocene or 

 Pleistocene age, and by recent gravel-deposits. The gravels, both in the 

 main valley and in the tributary streams, have yielded a considerable 

 quantity of alluvial gold, and are even yet in places profitably worked by 

 small parties. 



Devonian Pocks 



Fig. I. — Sketch Section across Reefton Goldfield. 



The above sketch section across the district from west to east indicates 

 the geological structure. 



* A. McKay, " Geology of Reefton District,". Reps. N.Z.G.S., 1882, p. 130. 

 I hoc. ciL, p. 108. 

 t Lor. cit.. p. 140. 



