Vol. 55.] ON PALEOZOIC KADIOLAEIAN EOCKS IN F. S. WALES. 19 



and chromite, as described by Mr. W. Anderson, late of the Geo- 

 logical Survey of New South Wales.^ 



In the Barraba a,nd Bingara districts radiolaria are present in 

 the form of chalcedonic casts in the red jaspers and in the dark- or 

 light-grey jasperoid claystones. They are in the best state of pre- 

 servation in the former, particularly in those varieties which are 

 most opaque, and which have suffered least from secondary silicifica- 

 tion. The thickness of some of the belts of red jasper amounts to 

 about 100 feet, but the average thickness would perhaps be con- 

 siderably less. The individual beds of which the jaspers are formed 

 are apparently thin, but owing to much superinduced lamination, 

 parallel to the bedding-planes, their original thickness is difficult to 

 ascertain. 



The radiolarian jaspers and claystones of Bingara and Barraba 

 are, as a rule, inclined at a high angle, with a prevalent strike of 

 N. 20° to 30° W. In the neighbourhood of Ironbark^ near Barraba, 

 the dip is 80° to 90° north-north-east. The series near Barraba is 

 not much folded. 



As regards the downward limit of the Barraba and Bingara 

 series, no basal beds are at present known, but detailed geological 

 mapping of this large and sparsely-populated area has not as yet 

 been attempted. ISTeither has any definite upward limit hitherto 

 been discovered, though it is probable that the series underlies the 

 bulk of the Lepidodendron australe-hQ^s. No physical break 

 between the radiolarian and the Lepidodendron ctits^raZe-beds, how- 

 ever, has as yet been traced. 



With regard to macroscopic fossils, it is doubtful whether any 

 which have been described from these districts belong to the jasperoid 

 series of Bingara and Barraba. Mr. G. A. Stonier has referred to 

 the occurrence of fossils at Crow Mountain, near Barraba. These 

 have been determined by Mr. W. S, Dun, as follows ^ : — 



' Crinoid stems ; Phillijjsia s^.; Fenestella; PolyporaoxPTiyllopora^ 

 Rliomhopora (?) ; Spirifer ; Syringothyris cf. cuspidata, Martin ; 

 Strophomena of. rliomhoidalis, var. analoga, Phill. ; Orihis resupi- 

 nata, Martin (?) ; Orthotetes (?) ; Productus, several species.' 



As, however, the rocks containing these fossils occur on the 

 W.S.W. side of the serpentine-dyke, and differ somewhat in litho- 

 logical character from the jaspers, which are so dominant a type 

 on the E.N.E. side, there is reason for assuming that they may 

 belong to a newer series, the dyke possibly marking the site of 

 a fault, with a downthrow to the west-south-west. 



I '(ii) Near Tamworth the radiolarian rocks are developed on a 

 grand scale. Their total thickness, including that of the inter- 

 calated tuffs, as measured by us, amounts to perhaps 14,220 feet. 

 There are good grounds, however, for supposing that the beds 

 have been duplicated by a great fault ; but even on this hypothesis 



1 Ann. Eep. Dep. Mines N.S.W. for 1888 [1889] pp. 179-182 ; ihid, 1889 

 []890]p. 230. 



2 Ibid. 1895 [1896] p. 168. 



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