706 NOTE ON DEVONIAN AND CAltBONlFEROUS FORMATIONS, 



east at about 80°, containing Carboniferous fossils as follows : — 

 Zaphrentis, Michelinia lenuhepta, Spirifera, Euomphalus, and 

 Loxonema. 



This is followed, to the west, by a conformable series of tuffs 

 and slates, the dip being in the same direction, and decreasing in 

 amount as we go west. 



There is a well-marked physiographic break at this point, pro- 

 bably due to differential erosion. 



The sudden discontinuity in the dip and the general appearance 

 of the country lead us to suggest a probable fault to the east of the 

 limestone, letting down the Carboniferous area. 



The lithological resemblance of the strata between Tamworth 

 and Carroll Gap to, and the continuity of its folding with the 

 Devonian series of Tamworth, as well as the marked discontinuity 

 with known Carboniferous to the west, leave little doubt but that 

 this series is of Devonian age. 



The presence of Carboniferous fossils f at the localities marked 

 on Fig. 1, suggests that the boundary is approximately as repre- 

 sented on that diagram. 



The Carboniferous series may be intruded by the porphyrite 

 indicated in the section. 



From this point, an alluvial Hat extends to a spot about two 

 miles west of Gunnedah, being only interrupted by a ridge of 

 aplitic granite three miles east of that town. At the western edge 

 of this alluvial plain, there occurs a stratified rhyolitic tuff, pro- 

 bably of Carboniferous age, which is overlaid by Permo-Carboni- 

 ferous Coal-Measures. Further to the west and south, these Coal 

 Measures are capped by Triassic sandstones and claystones, as at 

 Mullaley, where specimens of Stenopteris were obtained from a 

 well in the town itself. 



t The following have been recorded from Mt. Uriari by Mr. VV. S. Dun : 

 — Zaphrentis, Prodiictus /^emireticiUatus, P. lovgispmun, P. cf. Miirchisoni, 

 P. undatm, Orthis resupinata, 0. australis, Spirifer striata, S. pinguis, 

 Dielasma sacculum, Entolitim aviculatum, Aviculopecten sp. , Euomphalus 

 pentangulatus, Dentalium, Orthoceras sp.ind. 



