GEOLOGY AND PETROGRAPHY OF THE PROSPECT INTRUSION. 44 9 



T. W. Edgeworth David— Proc. Roy. Soc, New South 

 Wales, 1896. 



In his Presidential Address, Prof. David corrects Clarke's 

 errors, and shows that "the dolerite graduates into the 

 basalt," and that "both have intruded the overlying Wiana- 

 matta shales." There is also some description of the main 

 type of rock, and its decomposition. 



M. Morrison — Records of the Geological Survey of New 

 South Wales, Vol. vn, pt. 4 (1904), p. 241. 



A list of the dykes, necks and other masses of igneous 

 rock in the neighbourhood of Sydney, with a detailed 

 account of several of the less known localities. A list of 

 literature on the subject is given, which was of service in 

 compiling the present bibliography. 



3. General Description of the Mass. 



Prospect Hill rises sharply from nearly level country on 

 its western, southern and eastern faces, but its northern 

 slope is more gradual. As regards shape it may be com- 

 pared in plan to a rude shark-hook, the shank lying to the 

 east, the convex bend to the south. The depression in the 

 centre is drained northwards by a small creek which 

 ultimately finds its way into the Parramatta River. The 

 accompanying map (Plate XXXIV), will convey a more 

 accurate idea of the shape of the surface outcrop of the 

 igneous rock, and indicates by means of rough contour- 

 lines the elevation of the surface. The whole mass is 

 nearly two miles long by one mile wide ; and portions lying 

 to the east and south — the "shank" and "bend of the 

 hook" — are somewhat higher than the western part — 

 the "barb." 



Inspection of the map shows that there is an isolated 

 area of Wianamatta shale surrounded by exposures of the 

 igneous rock. Numerous sections show that nowhere in 

 this patch is the shale more than a few feet thick, and 



