ORIGIN OF LATERITE IN NEW ENGLAND DISTRICT, N.S.W. 239 



These tufts pass by insensible changes into a hard pisolitic 

 ironstone, like specimens V 7 and V 8 from Portion 530, Scone. 

 These specimens are of a deep brick-red colour consisting of a base 

 of brick-red earth enclosing segregated grains of magnetic 

 iron about the size of peas. Some of the pisolitic concretions are 

 haematite and others limonite, but the majority are magnetite. A 

 few minute fragments of fossil plants are observable in specimen 

 V 7, and angular grains of quartz are occasionally noticeable. 

 This rock is more or less cellular, the hollows, which are of 

 irregular shape, being lined or filled with spongy black oxide of 

 manganese. 



From the occurrence of fragmental vegetable remains it wovdd 

 appear that water has played some part in the formation of this 

 rock, but there can be little doubt that in its tirst state it was a 

 volcanic tuff. 



A variety deserving special notice is specimen V 22, which con- 

 tains a great deal of felsite. The possibility suggests itself of this 

 tuff* having been formed during the earlier part of the Tertiary 

 volcanic outbursts, when, as pointed out by Mr. Herbei't Cox, 

 F.G.S., etc.,* small eruptions of felspar preceded the far more 

 extensive outbursts of basalt. These felsite lavas are confined to 

 an area of about one square mile, as far as is at present known, 

 and have been explored at Bailey's and at the Shallow Lead at 

 Rose Valley, where the thickness of the sheet seldom exceeds 

 three feet. Rich stream tin wash has been woi'ked under this 

 felsite at Bailey's mine. 



STRATIGRAPHY. 



(a) The relation of the laterites to the basalts and their 

 associated fossiliferous beds can be best studied in the immediate 

 vicinity of Emmaville, where good sections are afforded by the 

 shafts sunk to win the stanniferous gravels, which underlie 

 the laterite and basalt. Such sections show that most of the 

 laterite rests immediately on the Tertiary sedimentary beds, but 

 that a small portion of it is separated from them by a sheet of 

 hard basalt. A good section showing the laterite capping the 

 basalt was to be seen in Mr. H. Jew's 220 feet shaft in Reynold's 

 Selection, near Emmaville. As there were no means of my de- 

 scending this old disused shaft, my section is from information 

 kindly supplied to me by Mr. H. Jew. I was able, however, to 

 examine the rocks in the .spoil banks round the shaft, and from 

 the nature of these, as well as from the surface evidence, I was 

 satisfied that the laterite here overlies the soft and hard basalt. 



At Foley's 120 feet shaft near Kangaroo Flat, the lateiite not 

 only overlies the basalt but is separated from it by a seam of 

 stanniferous sand and gravel. The upper gravel was worked at a 



* The Tin Deiiosi's of New South Wales. Journ. R. Soc. N. S. Wales, 1886, xx. p. 105. 



