17 



GENERAL NOTES MADE DURING A VISIT TO MOUNT 



SASSAFRAS, SHOALHAVEN DISTRICT, BY MESSRS. 



R. ETHERIDGE Junk., AND J. A. THORPE. 



By R. Etiieridge, Junk., Palaeontologist to the Australian 



Museum and Geological Survey of N. S. Wales. 



The following "Notes" were collected during a ten days' trip 

 from Tarago, on the Cooma Branch of the Southern Railway to 

 IMayfield, the residence of Mr. C. H. Roberts, J. P., on Boro Creek, a 

 tributary of the Siioalhaven Rivei', and thence to Mount Sassafras, 

 in the Parish of Sassafras, County St. Vincent. The rapid 

 movements of the party render the " Notes " but imperfect and 

 tentative at the best, but as such, it is hoped they may be found 

 of some service to future travellers in that district. 



Geology. — Between Tarago and Mayfield the country is gently 

 undulating, speaking generally, and but little rock is visible in 

 place, the aspect of the ground, however, is that generally assumed 

 by rocks of Silurian age, hidden by a surfacing of local drift or 

 wash. 



At Mayfield the configuration of the ground is more rugged, 

 grits, greywackes, and altered nrudstones Ijeing exposed along the 

 flanks and summits of the ranges, and these I take to be without 

 doubt of Silurian age. The average height of these ranges, taking 

 the Mayfield Trignometrical Station as an example, is aljout 

 500 feet above the flat, although of course some of the hills 

 ascend to a much greater altitude. 



Immediately opposite Mayfield Homestead pinkish ternary 

 granite occurs in the creek bed, and is traceable along the alluvial 

 flat for some little distance down the creek. 



In the home paddock to the west of the homestead occurs a low 

 hillock of ironstone. An opportunity did not permit of my 

 ascertaining the precise relations of this deposit to the surrounding 

 Silurian rocks. It may V)e a reef in them, or form a capping of 

 Tertiary ironstone, unconformable to the former, and I am rather 

 inclined to favour this view. In the Boro Creek, in a direct north- 

 easterly line from this point occurs a highly altered white siliceous 

 grit of a very remarkable character. The soil on the western 

 side of the Boro Creek is of a very sandy nature, of that peculiar 

 appearance assumed by drift derived from gi'anite disintegration, 

 and it is possible that a considerable area of that rock may be 

 concealed here. 



The track from Mayfield towards the Sassafras passes over 

 much of this sandy country, extending as far as the crossing over 

 the Boro Creek at Virginia Water, the residence of Mr. Peter 

 Roberts. Here a fine alluvial flat has been formed. From this 

 point onwards rough Silurian country is traversed as far as 



