240 THREAT SERPENTINE-BELT OF NEW SOUTH WALES, vi., 



best seen three miles suutli of Euiiibra homestead, and consisting 

 of a variety of pebbles and fragments of oolitic limestone. This 

 conglomerate forms the eastern side of "Black Mountain," the 

 remainder of which is largely composed of green felsitic tuft'. 



Less than half-a-mile south west of Eumbra homestead is a 

 small intrusion of a very decomposed but clearly recognisable 

 minette(l, Pt. iii., p. 697, and Plate xxvii., fig. 14). It forms an 

 outcrop only a few yards in length. Near the serpentine, south 

 of Back Creek, there also occur a few dykes of the dolerite (not 

 albite-dolerite) usually associated with peridotite in these 

 northern localities. 



North of Crow Mountain Creek, the same sedimentary forma- 

 tions continue beyond the Woods' Reef Road to the Nandewar 

 Range. Rocks, probably Carboniferous and also Devonian, occur 

 west of Woods' Reef, but have not been examined in detail. 

 Limestones of a blue argillaceous type, characteristic of the 

 Barraba 8eries, occur here and there. 



At Crow Mountain, Stonier reported the occurrence of a long 

 line of Tertiary gravels (21). These commence, as stated pre- 

 viously, east of the serpentine, but may be traced through the 

 low gap south of Crow Mountain, past Eumbra homestead, and 

 along the western face of the mountain, where, near Eumur 

 Creek, they form a thick, strong conglomerate with a ferruginous 

 cement. North of this, they are represented by a large area of 

 granitic sand. (Jutliers of the gravel, etc., are dotted here and 

 there down towards the Manilla River. Again, south of Woods" 

 Reef, the serpentine ridge is covered by Tertiary gravel filling a 

 noticeable gap, and issuing from a still more marked opening in 

 the jasper-hills behind. 



To the north-west of Crow Mountain, the Pahvozoic and 

 Tertiary formati(jns are overlain by basalt, which covers much 

 of the region between Woods' Reef and Barraba. This basalt is 

 discussed in a later section (see p. 276). 



Passing to the head of Cobbadah Creek, we note that this 

 stream, leaving the gabbro, enters a narrow gorge about a mile 

 in length, cut through hard tuft's of \'arious kinds, some of which 



