448 H. S. JEVONS, H. I. JENSEN, T. G. TAYLOR AND C. A. SUSSMILCH. 



Under t lie heading "Basaltic and Allied Rocks," (Litho- 

 logical characters, page 497) he distinguished ten varieties 

 of which the four following are found at Prospect : — 



Variety (a). Tough compact black rock, no traces of 

 crystallisation, .... a few grains of chrysolite 

 may with difficulty be distinguished. 



Variety (e). A dark bluish rock, finely porphyritic with 

 small points (not tables) of felspar. 



Variety (g). A porphyritic basalt in which augite and 

 felspar are both distinct and some of the crystals 

 of augite are a quarter of an inch long. 



Variety (h). A felspathic rock consisting almost purely 

 of thin tables of felspar aggregated into a moder- 

 ately compact rock, with occasional geodes of 

 smaller felspar crystals. Some small specks of 

 augite appear disseminated through it and more 

 resemble green earth than augite. 



Further he made a very interesting note: — "At Prospect 

 Hill the compact black basalt changes to a compact rock 

 with disseminated points of felspar; next to porphyritic 

 basalt with distinct crystals of both augite and felspar, 

 and next to the felspar rock (/?), in which augite is almost 

 wholly wanting." 



Dana also gives a sketch of columnar structure occurring 

 at Prospect, and explains a peculiar type of decomposition, 

 which will be referred to in a later section. 



Rev. W. B. Clarke — Report on the Southern Gold Fields 

 of New South Wales, 1860. 

 Clarke decided that Prospect Hill was composed of 

 "magnetic diorite .... which is probably the summit of 

 a concealed mass, submerged during the Carboniferous 

 period;" and assigned the basaltic border variety to a much 

 later intrusion. These views have not been upheld by sub- 

 sequent in vestigation under more favourable circumstances* 



