58 Notes on the Geology of the Country around, Qoulburn. 



his writings, but minute and accurate descriptions of many parts 

 have also been given. In fact his energy has left but a limited 

 field for future geologists in the regions which he has explored. 

 Therefore, though the following noies are original, they do not 

 necessainly touch upon a new subject. The object aimed at in 

 the coloured map is simply to fix the localities of a few geological 

 features which have been long since reviewed en masse. 



PHYSICAL STRUCTURE. 



I will first endeavour to give a brief outline of the physical 

 structure of the country, and afterwards sketch in its geology. 



The county of Argyle is an elevated table land, its altitude 

 generally exceeding 2000 feet above sea level. Its lcwest portion 

 is the Shoalhaven basin on the east ; its greatest elevation is on 

 the western side. The dividing range which separates the coast 

 drainage from that of the interior forms a curved boundary on 

 the north-west, where its slope on the Argyle side is drained by 

 the Wollondilly and its tributaries, the Cookbundoon River and the 

 Guinecor Creek. The Wollondilly rises in a recess or curvature 

 of the range, and at first flows south, then trends to~ the east, 

 just touching Goulburn, and finally curves northwards, forming 

 part of the county's boundary on the east, and receiving its two 

 tributaries from the westward ; that is, from the interior of the 

 semicircle which its course has thus described. The dividing 

 range, on reaching the southern half of the county forks into 

 two parallel branches, the one running from the Wollondilly to 

 Mount Alianoyoniga, a summit midway between Lake Bathurst 

 and Lake George, and throwing its waters on the east side into 

 the Mulwarree Ponds ; the other continuing along the border of 

 the county, passhig through Mount Cullarin, and eventually 

 bounding the western shore of Lake George. The arms of this 

 fork are about parallel, ranging north and south, and partly 

 enclose the drainage area belonging to Lake George. Erom this 

 lake northwards the county is a succession of alluvial plains and 

 shallow lagoons ; and the drainage of the northern portion of 

 this tract escapes into western waters. 



In the eastern half of the county a rauge of hills runs from 

 near Lake Bathurst to Towrang Hill on the Wollondilly, thus 

 forming a line of separation between the waters of the Shoal- 

 haven and the Mulwarree Ponds. At Towrang the Wollondilly 

 has made a breach through this range ; and north of the river 

 the line of hills which mark its continuation lies inside the semi- 

 circle before alluded to. When viewed from Groulburn Plains 

 this continuation forms a striking object ; it stands out as a bold 

 lofty shoulder, called the Cookbundoon Eange. From near 

 Towrang the watershed between the Shoalhaven and Wollondilly 

 basins trends to the north-east. 



