332 C. A. SUSSMILCH AND W. G. STONE. 



GEOLOGY OF THE JJENOLAN OAVES DISTRICT. 

 By O. A. Sussmilch, f.g.s., and W. G. Stone. 



With Plates LV, LVI. 



[Read before the Royal Society of N. S. Wales, December 1, 1915. .] 



Part I. General Geology. 



By C. A. Sussmilch. 



A. Introduction. 



B. Previous Observers. 

 C Physiography. 



D. General Geology. 



(a) The (?) Ordovician Strata — The Radiolarian Cherts. 

 (6) The Silurian Strata. 



1. The Limestones. 



2. The Slates. 



3. The Quartzites. 



4. The Rhyolite Porphyry, 

 (c) The Igneous Intrusions. 



1. The Andesites. 



2. The Quartz Porphyrites. 



3. The Felsites. 



4. The Diorite. 



A. Introduction. 

 The field work upon which this investigation is based was 

 started some ten years ago for the purpose of providing 

 practical field instruction for the students of the geology 

 classes of the Sydney Technical College. On each sub- 

 sequent annual visit a few days have been spent in con- 

 tinuing the work, but as the time available was always 

 short, and as much attention had to be given on each visit 

 to the demonstration of ordinary geological principles, the 

 work has necessarily been slow and limited to that part of 

 the district immediately adjoining the Oaves. 



