KOTES AND EXHIBITS. 403 



and Mt. Flalierty. Tlieae are broken and tilted, often vertically, 

 by more recent porphyries and granites, upon whicli, as also 

 on the upturned edges of the Devonian strata, there rests an 

 irregular conglomerate of earthy matter, sand and pebbles, of a 

 dark greenish brown, which bleaches to a pale buff for about 

 twenty feet from the surface. The pebbles are derived, as is 

 shown by the fossils which they contain, from the older Devonian 

 rocks, which formed not only the bottom, but also shores and 

 islands in the carboniferous sea of this District. Many bands 

 of shales containing remains of plants, as well as of sandstones 

 containing characteristic marine carboniferous fossils are inter- 

 calated in various places with this conglomerate. Above it are 

 aluminous shales which in many places, as near Ben Bullen, have 

 fretted away under atmospheric action, and left the overlying rocks 

 with very insufficient support. These are close-grained massive 

 sandstones cleaving naturally into more or less rectangular blocks, 

 which, owing to the decay of their foundation, are now poised 

 on pedestals or overhanging caverns in a very picturesque way. 

 In these shales are abundance of plant remains, belonging to the 

 Newcastle beds. Above the sandstone, coal-seams appear at 

 Wallerawang and to the northward, while the series is closed by 

 the castellated walls of Hawkesbury sandstone which crest and 

 protect the whole. Indeed, at Blackman's Crown they are seen 

 to rise almost vertically above their deep Devonian foundations, 

 displaying in a landscape of extraordinary singularity and beauty 

 a diagram of perhaps equal interest to the geologist. The lime- 

 stone two miles N.AY. of Piper's Plat varies from a black knotty 

 rock to crystalline or even saccharoid marble. Its surface as 

 exposed in the quarries has been protected from the action of 

 running water, as is usual in limestone river beds, by deposits of 

 gravel (partly also in all probability by various vegetable 

 growths). Underneath, however, the acid waters flowing freely 

 along the joints of the rock have eroded them out into holes and 

 passages. These have subsequently, under a diminished flow, 



