260 T. W. EDGEWORTH DAVID. 



Creek Coal-measures, which form part of the Talbragar Coal-field. 

 The latter, however, may be an outlier. From the head of the 

 Talbragar northwards the coal-basin becomes somewhat contracted 

 in width from east to west, as towards the west it becomes rapidly 

 overlapped by the red soil formation of the Western Plains, which 

 latter is probably of late Tertiary age. From here it extends in 

 a comparatively narrow strip, as already explained by way of 

 Gunnedah and Warialda to the Queensland border. 



Of the small outlying coal-fields perhaps that of the Ward's 

 River, near Stroud, is the most important, and therefore deserves 

 special mention. 



Although geologically united the main basin is divided geo- 

 graphically into several distinct coal-fields, owing to the measures 

 being capped in places by new formations of sedimentary, or 

 volcanic origin. The main basin may therefore be conveniently 

 divided into the following fields : — 



f(l) The Hunter River Coal-field. 



(2) The Sydney Coal-field. 



(3) The Illawarra Coal-field. 

 M . -d . J (4) The Mittagong Coal-field. 



1 : ' ! (5) The Blue Mountain Coal-field. 



(6) The Talbragar Coal-field. 



(7) The Namoi (Gunnedah) Coal-field. 

 ,(8) The Gwydir Coal-field. 



Outlier (9) The Ward's River Coal-field, near Stroud. 



Coal-fields (1), (2), (3), (4) and (5). 



The first five coal-fields are so intimately related to one another 

 that it will be more convenient to consider them together than 

 separately. In the Hunter River Coal-field, where the formations 

 belonging to this group are most typically and extensively de- 

 veloped, the following classification of the formations is proposed 

 based on the observations of the Rev. W, B. Clarke, Mr. C. S. 

 Wilkinson, f.g.s., Mr. Wm. Keene, f.g.s., Mr. J. Mackenzie, f.g.s., 

 Mr. R. Etheridge junr., and many others; the formations being 

 ranged in descending order : — 



Feet. Inches — Thickness. 



1,150 (about) — Newcastle Series, productive coal-measures 

 containing an aggregate of over 100 feet of coal, with- 

 out considering seams less than three feet thick. 

 Characteristic fossils Glossopteris, Vertebraria, Noeg- 

 gerathia, Gangamopteris, etc. A fossil forest of con- 

 iferous trees occurs in the upper part of these measures, 

 the woody material having been converted into wood- 

 opal, and dark chalcedony. 



2,000 (about) — Dempsey Series, freshwater beds containing a 

 flora similar to the preceding, but not productive coal. 



