578 GREAT SERPENTINE-BELT OF NEW SOUTH^WALES, V., 



ill Long Gully, Cleary's Gully, the small gorge in portion 246, 

 and again in Spring Creek in portions 148 and 237, and is suffi- 

 ciently indicated in the map herewith (Plate 1.). The agglomerates 

 are interstratified with mudstones, and these also show dips con- 

 formable with those of the underlying rocks. The small gorge cited 

 above shows a very instructive exposure of these rocks. Again, as 

 mentioned by the previous authors, there are frequently short irre- 

 gular beds of pebbles in the agglomerates (9, p. 23), and if these 

 represent the bedding-plane of the agglomerates, as observations 

 at Borah Creek Gap, in the Baldwin Mountains, near Manilla, 

 convinced the present writer that they do, there is additional proof 

 of the conformity here claimed. 



The mode of origin of the agglomerates is not directly obvious. 

 They consist of fragments of chert, andesite, porphyrite, kera- 

 tophyre, and rhyolite, with some limestone, set in a matrix exactly 

 similar to that of the normal pyroclastic rocks, which is made up 

 of close packed fragments of crystals and rocks, evidently derived 

 from rocks of the same nature as those which occur as included 

 pebbles. These pebbles are frequently very smooth and rounded, 

 particularly in the lower portion of the series, though some angular 

 blocks occur. Professor David was of the opinion that they were 

 waterworn in many cases, but was doubtful whether magmatic cor- 

 rosion had not played some part in the roundmg of some of the 

 larger blocksO). The boulders and fragments reach a diameter of 

 nearly a foot in the neighbourhood of Cleary's Hill, but diminish 

 in size as they are traced to the north-west or south-east, and are 

 rarely more than half-an-inch in diameter, where the rock appears 

 on the railway-cutting by the Two-Mile Bridge, or in the valley of 

 Spring Creek. The source of these boulders was, therefore, in the 

 neighbourhood of Cleary's Hill. 



In many features these agglomerates are analogous to those pre- 

 viously described (p. 574), but differ from them in their immense 

 thickness, which reaches a maximum in the Tamworth Common of 

 nearly 2000 feet, but dies out by interdigitation with Barraba mud- 

 stones. Tliese interstratified mudstones are richer m Lepidoden- 

 dron than any other rocks in the district, and casts of this plant 



