180 ON THE GEOLOGY AND PETROGRAPHY OF BATHURST, N.S.W., 



shows the channel of the Macquarie in typical granite rocks. A 

 short distance down stream (Fig. 2) the river passes into silurian 

 slates, dipping at a high angle. The same sharp contrast extends 

 through the country, as a whole, and may be studied to advantage 

 in the hills about Cow Flat to the south of Bathurst, and in the 

 Winburnclale Creek, some seven miles to the north of the same town. 

 Immediately round Bathurst the granite is overlain by detrital 

 deposits, varying in age from pliocene to the most recent, or now 

 in process of formation. This applies especially to the strip of 

 country, including that on which Bathurst stands, between the 

 chain of the Bald Hills and the Macquarie River. Deep water- 

 courses have cut through these deposits, exposing beds of allu- 

 vium from two to fifteen feet in thickness, or decomposed granite 

 in some instances to a depth of thirty feet. That these erosions 

 have been effected rapidly, that is within the past fifty years, can 

 be readily proved. Some of the old settlers recollect a time 

 when many of these creeks were shallow water channels. Roots 

 of, comparatively speaking, young trees may oftentimes be seen 

 stretching from one wall of these gullies to the opposite one, 

 showing that the very beginning of the erosion must have taken 

 place at a time when the trees were fairly grown. It is impossible 

 not to be struck with the resemblance, in miniature, that some of 

 these creeks with their vertical walls bear to the canons of Colorado. 

 The photographs exhibited, taken about one and a half miles to 

 the south-west, illustrate these features very clearly. The exact 

 locality lies between the racecourse and the slopes of the Bald 

 Hills. The oldest of these detrital deposits are, undoubtedly, 

 those that flank the Bald Hills, and the more recent are those 

 that form terraces to the present river. Further on we shall see 

 that the line of basalt that crowns the ridges of the Bald Hills 

 marks the course of the one-time bed of the Macquarie. From the 

 time it occupied this position, the river has, at various intervals 

 eroded channels over the whole country between the Bald Hills 

 and the opposite slopes of the valley. In this way are accounted 

 for, the beds of shingle, gravel, and detrital matter that 

 conceal the granite. Large deposits of shingle and water-worn 



