Norman Taylor — The Cudgegong Diamond Field. 401 



various materials which compose the ancient river gravels, as well 

 as of those of more modern origin. 



The Cudgegong Eiver rises in the acute angle, open to the west 

 and north-west, which the Great Dividing Range forms in latitude 

 83° south, and the first part of its course is westerly about 30 miles 

 to Cudgegong village, and north-westerly 37 miles to the junction 

 of the Wialdra or " Eeedy Creek." In this part it is bounded on 

 its eastern side by the Dividing Eange, which presents a summit 

 of horizontally-bedded Carboniferous rocks, with Coal-seams and 

 Glossopteris shales, and from which, farther eastward, rise the heads 

 of the Hunter Eiver, the basin in which most of the celebrated Coal- 

 seams of N. S. Wales occur. The range, in its continuation south- 

 wards, completely encircles the heads of the Cudgegong Eiver, and 

 presents a similar formation of Carboniferous rocks, which occur in 

 great force on the upper sources of the river, the Hawkesbury 

 sandstones overlying them. The Carboniferous rocks only reach, 

 along the course of the river, on its north side, westerly to Eylstone. 

 Several outliers and cappings of basalt also occur on summits and 

 spurs of the Dividing Eange, as at Mount Bocoble, and elsewhere. 

 The main area of the basin, and the ridges which confine it on the 

 south and west, consist of tilted slate and quartzite, with a few 

 interstratified, and lenticular, bands of fossiliferous limestone. These 

 beds are either of Upper Silurian or Devonian age, but most 

 probably the latter, as the late Professor Thomson discovered the 

 distinctive Devonian genus Calceola in the limestone of Mount 

 Frome near Mudgee. Both formations may, however, be repre- 

 sented. These rocks are penetrated in places by small areas of 

 granite, greenstone, quartz-porphyry, and felstone. At the Wialdra 

 Eeedy Creek junction, near which the diamond drift first sets in, 

 the river suddenly bends to the south-west and south, and follows 

 that direction to its junction with the Macquarie Eiver, about 28 

 miles distant. These distances are as the crow flies. This part of 

 its course presents a structure similar to that of the older portions 

 of its upper basin, with the exception that limestone bands are 

 wanting, and no members of the Carboniferous series, except some 

 doubtful outliers to the north-west of the " Two-mile-flat," occur. 

 The whole course of the river is through a rugged mountainous 

 country — the only large flats being situated on and above the 

 diamond field. 



Outliers of Carboniferous rocks, consisting of sandstones, con- 

 glomerates, and shales containing Glossopteris and other plants, 

 form links, at trifling intervals, along the eastern watershed ; con- 

 necting the Carboniferous formation of the Dividing Eange with the 

 Coal-measures of the Talbragar district to the north. A few miles 

 north of the junction of the Eeedy Creek with the Cudgegong Eiver, 

 the Carboniferous beds form horizontal cappings on hills of slate 

 and granite, with quartz reefs and limestone bands, as at Tallawaug ; 

 whilst at Guntawang, to the south, and higher up the river, some 

 doubtful members are met with in the river valley ; and near the 

 junction they occur at a similar low level, and have been covered 



DECADE II. VOL. VI. — NO. IX. 26 



