224 GREAT SERPEXTIXR-BI'.LT OF XEW SOUTH WALES, vi., 



account of the later sedimentary rocks and the numerous igneous 

 rocks. This was accompanied by a map and sections which are 

 reproduced herewith [Plates xix. and xx.] (1, i.). In the third 

 article (1, iii,), a detailed petrological description was given of 

 most of the rock-types developed in the area: but, so far, no 

 account has appeared of the field-observations upon which these 

 general descriptions and map were based. The area is large (over 

 1 000 square miles), the survey was perforce rapid, and it was 

 intended to revise it in more detail. But since work in other 

 portions of the Serpentine Belt has confirmed the general cor- 

 rectness of the conclusions reached, and has opened up so many 

 new questions, for the solution of which there seems little evi- 

 dence in the district between Manilla and Bingara, it has seemed 

 best to publish the following account of the exploratory survey 

 of that district, while detailed investigation will be confined, for 

 some time, to the regions further to the south. 



Historical Introduction. 



The earliest references to this region are apparently Sir T. L. 

 Mitchell's brief notes on the trachytic ranges about Mount 

 Lindesay, near which he passed in the summer of 1831-2(2). 

 Eleven years later, Dr. Leichhardt passed down the Horton 

 River, noting the occurrence of Lepidodendron, the crinoidal and 

 brachiopod limestones, the Rocky Creek conglomerates, and 

 describing the volcanic rocks of the Nandewar Mountains (3). 

 The discovery of gold brought a rush to the Bingara district in 

 1851, and Commissioner Bligh w^-ote a brief account (with map) 

 of the geology of that neighbourhood in 1852(4). In the follow- 

 ing year, the Rev. W. B. Clarke passed through the north-eastern 

 and central parts of the region, noted most of the formations 

 here described, and, in particular, recognised the similarity 

 between the geology of Bingara and Nundle, and the probably 

 Devonian age of the limestones at Bingara (5). In the same 

 year, Stutchbury investigated the Horton River valley, and the 

 regions west of it, obtaining a large fauna from the beds now 

 considered to belong to the Carboniferous Burindi series, but 



