554 GEOLOGY OF THE WESTERN COALFIELDS, 



Perhaps it was this very superficial deposit, especially where 

 much hardened by silica, that so defended the bed o£ the ancient 

 Talley from atmospheric erosion, that it ultimately came to stand 

 out in relief above the areas over which much harder rocks had 

 been slowly broken down and removed. Soluble as limestone is, 

 it frequently appears in the f oi'm of ridges rivalling in height the 

 ranges among which it appears, and which have evidently been 

 formed by erosion. 



The Coco where we cross it is bordered on both sides by the 

 Slates, which show caves in their precipitous faces, and the 

 Limestone reappears again beyond it. At Mr. Maclean's, eight 

 miles as the crow flies, and something more like eighteen by the 

 road, these Slates and Limestones disappear, and are succeeded 

 by the Quartzites, dipping to the West. This would seem to 

 indicate a great fold. But the time at my disposal was too 

 limited to allow for more than a cursory glance at the country, 

 or to pursue the road any further. 



Mr. Maclean informed me that these quartzites continue for 

 some six miles further, until the level country is reached. The 

 rock there is freestone. To whatever formation it may belong, 

 it has certainly nothing to do with the Hawkesbury sandstones, 

 as it obviously underlies the Marangaroo conglomerate, or its 

 equivalent. It seems probable that it may be some portion of 

 the lower marine carboniferous beds. It is said to contain fossils. 



Mr. Maclean further states that the sandstone ranges which 

 separate the main valleys, as of the Capertee and the "Wolgan, 

 and their spurs of equal elevation which divide minor basins, are 

 really and truly wcdls, much higher than they are broad, often 

 not more than from one hundred to twenty yards in width, and 

 with sides, as we see, perfectly vertical. Something of this 

 structure may be observed from Crown ridge on a day when the 

 landscape is brought into perspective by the shadows of drifting 

 clouds. But on a bright day the succession of summits shows 



