BY A. B. WALKOM. 159 



Summary. — Representatives of two Systems — Carboniferous and 

 Permo-Carboniferous — occur in the district described. The Car- 

 boniferous rocks all belong to the Upper Carboniferous, some 

 being of the same age as the Clarencetown tuffaceous sandstones, 

 etc., and others of the same series as the rhyolites, etc., at Mount 

 Bright, near Pokolbin. The boundary between the two Carboni- 

 ferous series is formed by an extensive E.-W. fault (the Webber's 

 Creek fault), throwing to the south. 



The Permo-Carboniferous rocks occur in two separate areas. 

 Just north-east of Mount Tangorin, there is a small, triangular- 

 shaped basin made up of representatives of the Lower Marine 

 Series, Greta Coal-Measures and Upper Marine Series. The most 

 important point, economically, here is the occurrence of the Greta 

 Coal-Measures. Previously it was thought that this was just the 

 southern end of an extensive occurrence of the Coal-Measures, but 

 the discovery that it is a small isolated basin, shows that there is 

 probably no Greta coal anywhere to the north-east of the district, 

 and on the north-west, the next occurrence is somewhere not far 

 south-east of Muswellbrook. The small extent of the Cranky Cor- 

 ner basin, and its inaccessible position, make it improbable that it 

 will ever be of any considerable economic value. The other area of 

 Permo-Carboniferous rocks is just west of Brook's Mountain. 

 Here the Upper Coal-Measures are developed, enclosed on three 

 sides by heavy faults. Upper Marine Series (Crinoidal Beds) 

 occur farther to the west, on the western side of the Greta fault. 



My thanks are due to many of the residents of the district, who 

 were always willing to assist me as far as possible, and, in parti- 

 cular, to Mr Frank Drinan, of Glendon Brook, and Mr. J. Graham, 

 of Westbrook. I also wish to express my gratitude to Professor 

 David and Mr. AY. S. Dun for the interest they have taken in my 

 work, and for the help they have rendered me, in discussing and 

 criticising this work in preparation. 



EXPLANATION OF PLATE XIV. 

 Geological Map of the Glendonbrook District. 



