BY H. I. JENSEN. 583 



non-artesian. North-west, west and south-west the formations 

 are mainly artesian, Upper Triassic, strata."*^ 



For statistics concerning the output of the artesian Ijores near 

 the Warrumbungle area, see Allan's paper, f 



6. DiATOMACEOUS EaRTIIS AND OTHER MINERALS OF COMMERCIAL 



Value. 



(a) Diatomaceous Earths. — There are numerous deposits of this 

 mineral in the Warrumbungles. Professor David described one 

 occurrence at Wandiallabah Creek. | Here the earths are 

 associated with trachytic (sanidine) tuffs. 



Similar deposits in association with tuffs containing Cinna- 

 mornum Leichhardtii, Endiandra ^9r<:<^^j?t6e«s § and other leaf- 

 remains occur at Gowang not more than half a mile from the 

 station house at Keewong (or Gowang) Creek, and also on smaller 

 tributaries of this creek and of Bianaway Creek. These last- 

 named deposits are, however, thin and valueless. 



A very thick deposit of good diatomaceous earth occurs on 

 Chalk Mountain near Bugaldi. Its thickness is six feet or more, 

 and it is interbedded with basic tuffs below which there is a sheet 

 of phonolitic trachyte and above a sheet of vesicular basalt. 



* I am pleased to find that Mr. Pittman has also arrived at the conclusion 

 that the trachytes in the west of the Warrumbungles overlie the Triassic 

 intake beds of the artesian system. Mr. Pittman classes these rocks as 

 Hawkesbury (Records Geol. Survey N. S. Wales, Vol. viii. p. 187). In my 

 Preliminary Note I called them Trias- Jura simply on account of lithological 

 resemblance to the Trias-Jura rocks of South Queensland. I do not think 

 any very definite evidence of age has so far been obtained, except that they 

 cap the Pernio- Carboniferous unconformably, and are of fairly late Triassic 

 age. They also seem to me to merge into the Cretaceous to the north-west 

 of the Warrumbungles without any unconformity, but this point is doubtful. 

 The section of Tooraweanah Mountain in Mr. Pittman's paper is typical of 

 sections met with in numerous places along Uargon Creek, Wandiallabah 

 Creek, and at Gowang. 



t Allan, P., '"The Drought Antidote for the North-West, N. S! Wales," 

 Proc. Sydney University Engineering Society, Vol. xi., 10th October, 1906. 

 % These Proceedings, 1896, p 264. 

 § Deane, 11. , Records Geol. Snrv. N. S. Wales, Vol. viii. p. 191. 



