268 GREAT SERPENTINE-BELT OF NEW SOUTH WALES, vi., 



make a marked feature, over which the Horton River tumbles 

 in a high cascade. The headwaters of this river lie on basalt, 

 but it falls from thence over a highly prismatic layer on to the 

 conglomerate. The upper falls were described by Powell in 

 1889(42). Below the cascades, the floor of the Horton River 

 Valley is of low relief, cut in Burindi and Barraba mudstones, 

 which, north of Beeren, are invaded by quartz-porphyry. To 

 the east, the high range of the Blue Knob mass is capped by 

 the dolerite-sill, beneath which are Barraba rocks. 



The hill beside Horton Township is another sill of dolerite of 

 the Blue Knob type, about 300 feet thick. Its boundary has 

 not yet been mapped. The shales in the river are of the typical 

 Barraba-type, and contain Lepidodendron. (See Plate xx., fig. 2, 

 G, H). 



The area north of here was well described by 8tutchbury in 

 1852(6, a, b). The structure is shown in Plate xx., fig. 3. Omit- 

 ting, for the present, the western portion (see p. 271), we note 

 the syncline in the Rocky Creek conglomerates, that has been 

 traced up from Gunnedah, is maintained, and is clearly to be 

 seen in the gorge of Rocky Creek. At the western end of this, 

 the dip is to the east at about 25°, while, at the eastern end, the 

 dip is westerly at 35°, and increases in the underlying Burindi 

 mudstones still further to the east. The series is, in ascending 

 order : Burindi tuifaceous mudstones, followed by tuffs covered 

 by a very great thickness of coarse conglomerates with boulders 

 of granite, porphyry, and rhyolite in a tuffaceous ground-mass, 

 with interbedded layers of rhyolite and rhyolite-tuff. Following 

 this, there is more tuff, and above a band, about 50 feet thick, 

 of a hard cherty tuff, very fine-grained but including small 

 pebbles of granite, etc. Following this, is a mass of coarse 

 rhyolite-tuff. Altogether this series cannot be less than 2000 

 feet thick, and the hill, at the side, exposes at least 500 feet 

 more, which, however, have not been studied. 



East of the edge of the conglomerate, the dip rapidly increases. 

 The rocks are chiefly mudstone, but at Caroda, near the junction 

 of Rocky Cjreek and the Horton River, is a bed of oolitic 

 crinoidal limestone, noted by Stutchbury(6), and later by 



