444 PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 11, 



horizontal position on each other. At the junction of the Nattai the 

 lowest beds are seen dipping only slightly to the westward. 



Near the junction of Toonalli Eiver a dry creek intersects the beds 

 of a spur from Toonalli Mountain, locally called ^'The Peak of 

 Teneriffe." In this creek I found in undisturbed position white 

 and blue shales with Glossoj)teris. The bottom and sides of the 

 creek are encumbered with fallen blocks from the upper quartzose 

 sandstones and intermediate beds of similar kind below the Hawkes- 

 bury beds ; and amidst these blocks occur also others of inflam- 

 mable shale passing into Brown Cannel. The seam was ascertained 

 to lie between 900 and 1200 feet above the sea, and consequently 

 is not far from the base of the Hawkesbury rocks. There are on 

 the flat at the base of the spur several water-worn blocks of this 

 Cannel lying on the surface of the ploughed ground, which rests 

 upon a red and yeUow grit of the Upper Marine beds. These are 

 abont 9 inches thick, whereas up the creek the blocks reach a 

 thickness of 12 or 14 inches. Only one conclusion can be drawn 

 as to the blocks upon the flat — namely, that they have been drifted 

 by floods to their present position. It is quite impossible that 

 they could occur actually bedded as a coal-seam with the marine 

 beds without any accompanying shales or clays ; and it is equally 

 impossible that they can belong to one seam highly inclined, for 

 the beds have a dip, if any, in a contrary direction to the implied 

 upheaval. 



Nearly opposite the mouth of the Nattai, the Upper Marine for- 

 mation attains an elevation of 500 feet above the valley, so that 

 the three successive groups of beds have nearly equal vertical 

 dimensions. In a recess of the ranges near the head of Lacy's 

 Creek, the Middle or Coal-measure series is generally plainly exposed. 

 The junction of the latter with the Hawkesbury rocks is marked 

 by springs, and the regular stratification of the beds both above 

 and below this junction is remarkable ; their fall is about 100 feet 

 in succession, until the white shales are reached, where a similar 

 concealment to that on the Tonalli Eiver takes place, from detached 

 huge blocks of coarse grits and sandstones. 



A coal-seam, extremely Hke one of the Nattai seams, has strewn 

 its fragments on the ledge below the springs ; and blue shales and 

 mottled clays mark its position somewhat higher up. The blocks 

 that obscure the beds origin,ate in a system of three-jointed planes 

 cutting up the beds, which are thus rendered capable of supplying 

 materials for a debacle. 



7. FluviatiU Drift. — The river-bed and bottom of the WoUondilly 

 valley, for a depth of 40 feet and upwards, is covered by a fluvi- 

 atile drift of hard pebbles, chiefly porphyritic, with very little 

 granite, (probably because it easily disintegrates), some sandstone, 

 and coal mingled with sand. This drift I have traced along the 

 Warragamba, and the shoulders of the ridges above it, into the 

 Wianamatta region, across the latter in directions corresponding 

 with the WoUondilly and Goose, to Emu and Penrith, and across 



