261 



NOTE ON THE OCCURRENCE OF DIATOMACEOUS 

 EARTH AT THE WARRUMBUNGLE MOUNTAINS, 



NEW SOUTH WALES. 



By T. W. Edgeworth David. 

 (Plates xv.-xvii.) 



I. — Introduction. 



Deposits of diatomaceous eai'th have been recoi'ded as occurring 

 in New South Wales at the following localities : — Barr aba (between 

 Tamworth and Bingara); the Lismore District; the Richmond 

 River; the Tweed River; Cooma; Newbridge; and the Warrum- 

 bungle Mountains. The deposit near Barraba has been described 

 by Mr. E. F. Pittman, the Government Geologist, in general 

 terms.* 



Mr. Pittman states that the diatomaceous earth is capped by 

 basalt, and attains a thickness of about 8 feet, having a layer of 

 coarse sand (2 inches thick) about 3 feet from the top. The 

 infusorial earth rests on a bed of sandy mudstone, about 1 foot 

 in thickness, under which is an impui'e infusorial depositcontaining 

 rolled pebbles and fragments of imbedded lq,va, pointing to the 

 fact that volcanic eruptions were common at the time of its 

 deposition. Finally, an overwhelming flow of lava filled up what 

 was, doubtless, during the Miocene epoch, a lake, and it now 

 forms an elevated tableland. As far as I am aware, this is the 

 only reference to the mode of occurrence of diatomaceous earth 

 in New South Wales. Descriptions have been given by other 

 observers of hand specimens of the diatomaceous earth. 



Ann. Rept. Dep. Mines, 1881, pp. 142-143. By Authority. Sydney, 1882. 



