BY W. G. WOOLNOUGH. 787 



of 200 feet. Ill the conglomerates the most abundant pebbles 

 are of black graptolite-slate, reef-quartz, and quartzite. 



The upper portions of the cliffs forming the northern side of 

 the Shoalhaven Gorge are composed of white, coarse-grained 

 sandstone, very like Hawkesbury Sandstone in general appear- 

 ance. Mr. R. S. Bonney expressed doubt as to its Triassic age, 

 and succeeded in discovering the cast of a Spirifer (/S'. duodecim- 

 cosiatiisl) in the sandstone of Portion 15, Parish Bumballa, thus 

 proving its Permo-Carboniferous age. 



Like the Upper Marine Beds, the Upper Coal Measures con- 

 sist mainly of conglomerates and sandstones. Lithologically 

 there is no distinction between the rocks of the two horizons; 

 they can be separated only by stratigraphical evidence. 



At Coal Mine Hill there is a band of highly bituminous shale 

 passing into impure coal. This has been prospected by means of 

 an adit, now collapsed. The shales are crowded with fragments 

 of plant-fossils, none of which are sufficiently preserved for 

 specific determination. This shale-bed is evidently part of a well 

 defined coal-horizon, since at Tallong Station, two diamond drill 

 bores [lassed through a seam of inferior coal. The poor 

 quality of the coal is not to be wondered at, since it was pro- 

 duced at the very border of the coal-swamps, and, therefore, was 

 subject to contamination by land-derived material. 



Frequent intercalations of shale in lenticular beds are found in 

 the sandstones and conglomerates. These are crowded with 

 macerated plant-material, but only in one place, a limited bed in 

 the railway cutting just east of Tallong Station, have recognisable 

 fossils been obtained. At this point, plentiful leaves oitNoggera- 

 thiopsis occur with one or two specimens of Glossopteris. The 

 relative abundance of the former species may be explained by 

 the fact that the land to the south and west was clothe^^l with 

 coniferous trees like Araucarioxylon, which is now regarded as, 

 possibly, the parent-tree of Noggerathiopsis leaves. It is rather 

 remarkable that fossil coniferous wood is not abundant; probably 

 the stream-currents were strong enough to sweep fallen trees 

 further into the lagoons before they became water-logged, while 



