118 me. w. j. cltjnies ross os the [May 1894, 



of what is now Bathurst, aud least so to the east, where the lime- 

 stone is very little altered. The granite intrusion probably produced 

 an anticlinal, and raised the area above the sea. After a time 

 there was most likely a subsidence, but not at first a very great one, 

 and the central area may not have been submerged, since the 

 Devonian rocks, consisting of conglomerates, sandstones, and shelly 

 limestones, with plant-remains, were probably deposited in a com- 

 paratively shallow sea. There must, however, have been a very 

 great subsidence before the end of the period if, as Mr. Wilkinson 

 states, the Devonian rocks are 10,000 feet thick at Eydal. Near 

 Bathurst they have not been measured, but they do not appear to 

 be so thick as that. They may have been reduced by denudation, 

 but very possibly were originally thicker near Eydal than where 

 they abut against the Silurian uplift in the Bathurst area. 



It is uncertain whether the Devonian rocks belong to the 

 Lower, Middle, or Upper division of the system, but at the close 

 of the period there must have been a long interval during which 

 both Silurian and Devonian strata were greatly denuded, and the 

 granite exposed in places. This probably included the time when 

 Lower Carboniferous rocks were being deposited in other parts 

 of the colony. Then the Upper Carboniferous and Permian rocks 

 were foimed in the Lithgow district, but it is doubtful whether they 

 ever extended to Bathurst. 



What was the condition of the Bathurst area during the Meso- 

 zoic and early Tertiary periods there is no evidence to show. Just 

 east of Lithgow, the Hawkesbury Sandstone (probably Triassic) 

 occurs, of great thickness, and this very possibly once extended 

 much nearer Bathurst than it does now. There is, however, 

 a great gap in the geological history of the district until we come 

 to late Tertiary times. We then find evidence that the streams 

 ran over granite beds in much the same courses as they do now, 

 but the country as a whole was probably a good deal more elevated 

 than it is at present. Volcanoes burst out somewhere in the 

 district, and there may have been several centres of eruption. 

 Floods of lava were sent down the channels of the streams, sealing 

 up the drifts under thick layers of basalt. 



Since the volcanoes became extinct, subaerial denudation has 

 gone on steadily. All the high ground around the streams has been 

 swept away, the materials going to increase the great deposits of 

 drift-earth far to the west. Most of the basalt has also gone, 

 only the outliers on the Bald Hills, and on a few other small hills 

 in the neighbourhood, remaining to indicate the course of the old 

 river- channel, now become a hill. As the stream or streams shifted 

 their course and cut their channels deeper, they left terraces of 

 gravel to mark the successive heights at which they flowed. 



There is a popular tradition that the Bathurst Plains were 

 formerly covered by a lake, but there does not seem to be any 

 evidence in support of this. No doubt, in wet years, much of the 

 low ground around the channel of the Macquarie, and between the 

 low hills, may have been covered by water for some time. By the. 



