580 GREAT SERPENTINE BELT OF NEW SOUTH WALES, ii., 



to occur further north), as to make it advisable to call attention to 

 their differences. These are not very great. The spilites are pre- 

 sent in much greater abundance, as far as is known, in the upper 

 breccias than in the lower, a discordance in character that is signi- 

 ficant only because the discussion is on the relationship of two 

 adjacent series. High spilite-content is not a general character- 

 istic of the Upper Series, for this lava is much less common in the 

 series at Tamworth, which is considered identical with the Upper 

 Bowling Alley Tuff-breccias and chert. Secondly, the peculiar 

 coarse breccias, and large chert-fragments characteristic of the 

 upper part of the Upper Breccias, are not at all common in the 

 upper part of the Lower Breccias, nor has Lepidodendron been 

 found yet among these. 



It is very probable, however, that the whole belt of Bowling 

 Alley rocks is traversed by a series of parallel, overthrust faults, 

 so that what appears to be a single portion of the series, e.g., the 

 Lower Breccias, may be thickened by many repetitions. This 

 would account for the very frequent interbedding of breccia and 

 claystone throughout. Also the multiplication of spilite-flows 

 might be explained thus. 



The strike of these beds is generally parallel to that of the ser- 

 pentine-line, and swings to the north and south direction sympa- 

 thetically with the serpentine on Oakenville Creek, where a dip 

 W.5N. at 70° has been observed. Generally speaking, the lower 

 breccias and claystones have a very steep easterly dip (70°-90°), 

 the limestones very little to one side or the other of the vertical, 

 while the upper claystones and breccias have a slowly decreasing 

 angle of dip to the west. Minor contortions occur here and there. 



The chief difference throughout, between this series and the 

 Tamworth beds with which they are correlated, lies in the apparent 

 absence of the small lenses of radiolarian limestone. These are not 

 very obvious in a rapid survey of the Tamworth region itself, and 

 it is quite possible that they may occur in the Nundle region, but 

 have been overlooked. Spilitic rocks are much more frequent, 

 however, than at Tamworth. 



