BY PROF. DAVID, RICHARD HELMS, A\D E. F. PITTMAN. 29 



towards Jindab3'ne there is a strong outcrop of these sedimentary 

 rocks. 



At 9 miles granite of the Kosciusko Phxteau type first makes its 

 appearance. It has the general aspect of being newer than the 

 gneiss of Cooma. An actual junction, however, between the two 

 was not observed. This granite continues, with occasional 

 cappings of basalt and Tertiary gravels at the points shown on the 

 section to about half a mile beyond Berridale, a total of 21 miles 

 beyond Cooma. At the latter spot there is a sharp junction line 

 between this granite and some black chiastolitic shales and 

 radiolarian cherts. The altitude of this junction line on the 

 main road is about 2,530 feet. The chiastolite slates and shales 

 here dip N. 15° W. at 70^. At 22|- miles an interesting lake, Lake 

 Coolapatong, is seen about half a mile to left of the road. One of 

 us (Mr. Helms) has suggested that it may be of glacial origin. 

 Its altitude is approximately 2,400 feet. 



At Barney's Ridge, from 24 miles to 27 miles, 15 chains from 

 Cooma, there is a great development of radiolarian cherts and 

 shales. As these are striking in the direction of Stockyard Creek, 

 Byadbo, where Mr. J. E. Carne, F.G.S., has discovered, in rocks 

 lithologically identical, numerous Lower Silurian graptolites (47). 

 There can be little doubt, we think, that these rocks too at 

 Barney's ridge are Lower Silurian. This supposition is much 

 strengthened by the recent discovery by Mr. W. S. Dun, 

 Palaeontologist to the Geological Survey of New South Wales, of 

 abundant casts of radiolaria in the graptolite shales of Byadbo, 

 similar to the casts in the Barney's Ridge cherts. 



The latter, moreover, closely resemble the Lower Silurian 

 graptolitic cherts and shales of Mandurama in New South 

 Wales, in which one of us (Mr. Pittman) has discovered and 

 described Lower Silurian graptolites. 



The chalcedonic pseudomorphs after radiolaria in the cherts at 

 Barney's Ridge vary from 0-75 mm. to 0-150 mm. in diameter. 

 By far the greater number are exactly 0*115 mm. in diameter. 

 The casts are all more or less spherical. 



