20 PEOP. T. W. E. DAVID & MR. E. E. PITTMAN [Feb. 1 899, 



the thickness would still amount to about 9260 feet, and no upward 

 or downward limit to the series has yet been discovered. The 

 details are shown in the accompanying section (PI. III). The height 

 attained by the beds above sea-level varies from 1220 to 2570 feet. 



"With the exception of some wide strips of post-Tertiary alluvium 

 along the course of the Peel and Cockburn Rivers, the sedimentary 

 rocks of this district are wholly Paloeozoic. The series examined by 

 us is bounded on the north-east by a large mass of intrusive granite. 

 The granite is ternary, passing near its junction with the sedimentary 

 rocks into an aplitic type. Sphene has lately been observed by 

 Mr. G. W. Card, Mineralogist to the Geological Survey of New 

 South Wales, in part of this granite on the Government Tobacco 

 Farm, near Tamworth, It occurs in comparatively large crystals, and 

 frequently idiomorphic, in abundance as an accessory mineral. The 

 rock also contains hornblende as well as biotite. At the boundary of 

 the granite, as shown near the eastern end of the section (PI. Ill) 

 the sedimentary rocks dip underneath it, which is suggestive 

 of the massif having the structure of a laccolite, or possibly that 

 of a huge sill. In close proximity to its margin is a bed of 

 limestone, varying from 50 to over 100 feet in thickness. Traced 

 northward to Moor Creek its thickness increases considerably, and 

 in places must be about 1000 feet. 



The limestone has been converted by contact-metamorphism into 

 a coarsely crystalline, saccharoidal marble, with an abundant fibrous 

 white mineral (tremolite ?) and garnets. Nearly all traces of the 

 structure of the organisms which have contributed to form this 

 limestone have been obliterated through metamorphism, with the 

 exception of some imperfectly-preserved specimens of corals refer- 

 able to the Favositidse, including Favosites, Alveolites alveolaris, 

 an external cast of Biphi/phyllum, some badly-preserved casts of 

 what Mr. W. S. Dun considers to be probably Pentamerus^ and 

 abundant casts of crinoids. This limestone-bed has been folded into 

 an anticline, the arch of which has subsequently been removed by 

 denudation. On following the bed northward for a mile from its 

 bold outcrop west of Carmichael's homestead, we found that it 

 gradually bent round in a curve towards the west and south until 

 it ultimately assumed a reversed dip which was west-south-west 

 at 55° where it crossed the line of section. The strata intervening 

 between this limestone-bed and the thin bed of radiolarian lime- 

 stone marked G (Pi. Ill) consist chiefly of claystones, black cherts, 

 radiolarian limestones, and tuffs, similar to those constituting the 

 greater part of the sedimentary rocks in the section at Tamworth 

 Common about to be described. The aggregate thickness of these 

 strata amounts to about 4150 feet. 



The claystones are similar in lithological character to those 

 above mentioned near Bingara and Barraba, but the radiolaria 

 appear to be better preserved in the Tamworth rocks. Red jaspers 

 are not represented. As a general rule, the radiolarian rocks 

 are sufficiently soft to admit of being scratched by steel. The 

 section above the limestone, if taken in ascending order, shows 



