by t. w. edgeworth david. ' 561 



2. Localities and Geological Horizons of Radiolarian 

 Rocks in New South Wales. 



With the exception of the opal rocks which contain numerous 

 spherical casts, possibly of radiolaria, all radiolarian rocks at 

 present known in N.S. Wales are of Palaeozoic age. Radiolarian 

 I'ocks have so far been discovered by me in N.8. Wales at four 

 different localities — (1) Bingera, (2) Barraba, (3) Tarn worth, (4) 

 Jenolan Caves. (See Map, Plate XL., fig. 3.) 



Devonian. (1) — (1) Bingera and (2) Barraba. In my Address* to 

 this Society in 1894, I stated "in tlie New England District of 

 N.S. Wales possibly the red jasperoid shales of the Nundle and 

 Bingera Districts with the associated serpentines may represent 

 altei'ed abysmal deposits, as has been suggested by Captain 

 Hutton for similar rocks in the Maitai Series of New Zealand, 

 unless the red claystone represents rock locally metamorphosed 

 where in contact with the serpentines." 



Since reading the above Address, as opportunity offered, I have 

 from time to time studied the red jaspers of Barraba and Bingera, 

 by means of microscope sections. These revealed the presence of 

 numerous spherical bodies composed of translucent chalcedony, 

 distributed through an opaque groundmass of red jasperoid material. 

 It appeared probable that these were internal casts of radiolaria, 

 but the evidence was inconclusive. Last January, through the 

 kindness of Mr. J. J. H. Teall, F.R.S., I was allowed to examine 

 his carefully prepared microscopic sections of the Lower Silurian 

 radiolarian cherts from Mullion Island, off Cornwall, and from 

 the Culm of Devonshire, as well as sections of red radiolarian 

 jasper from the Antarctic regions. It was at once obvious that 

 the last mentioned rock in particular closely resembled the 

 Bingera and Barraba red jaspers. On my return to Sydney, last 

 March, with the help of the third year University students, I 

 resumed my examination of the New England red jaspers. Dr. 



P.L..S.N.8.W. Ser. 2, Vol. viii. p. 594. 



