BY W. N. BENSON. 525 



So far as I know, this is the whole of the work that has been 

 done on the Newbridge district; and no detailed description or 

 map of the formations as a whole lias yet appeared. 



ii. — The Andesites and Asbestos. 



The south-w^estern portion of the Parish of Galbraith is andesite. 

 At its contact with the slate it becomes laminated and very 

 decomposed, so that the distinction between decomposed slate 

 and decomposed andesite is often difficult. It is, therefore, not 

 quite certain whether the andesites are intrusive into or inter- 

 bedded with the slates. I have not noticed branching andesite 

 veins, as might be expected in an intrusion ; and there are 

 frequent examples of long, narrow bands of slate among the 

 andesite. These Newbridge andesites appear to be continuous 

 with those of Cadia, and their microscopical characters are similar. 

 The Cadia andesites are stated by Mr. J. B. Jaquet to be inter- 

 bedded with the slates.* I, therefore, am inclined to believe 

 that the slates are interbedded with the andesites, that is, the 

 andesites formed a series of contemporary flows. In the absence 

 of any fossils in the adjacent slates, we cannot sa}^ whether the 

 i^lates are Silurian or Ordovician. Mr. Jaquet classes those of 

 Cadia as Ordovician. 



The boundary of the andesites crosses the Trunkey Road near 

 the southern limit of the Parish. It runs from there up to the 

 point where the railway crosses Reedy Creek. Thence it runs 

 in a north-westerly direction for about three miles, beyond which 

 it was not traced. The rock outcrops fairly well near the 

 boundary, but away from it the outcrops are few. The rock- 

 mass as a whole must be fairly porous. A strong spring of pure 

 water runs (September) at the top of Smith's Hill. 



An exact petrographical description of the Smith's Hill 

 andesite is as follows : — 



MacroscopicaL — Hard, compact, light green rock, with pyroxene 

 and felspar phenocrysts. 



* " Iron Ore Deposits of New South Wales," 1901, p. 21. 



