66 Proceedings of the Royal Society of Victoria. 



sunk to ascertain the depth of the drift. Eighty-one holes, 

 aggregating 827 feet, have been sunk to ascertain geological 

 boundaries and for prospecting." With regard to the hill- 

 shading and the topography generally, the maps are marvellously 

 accurate. Every little rise and gully is exactly shown, and J 

 have been constantly able, map in hand in the field, to mark my 

 position accurately to within a few yards. Without these maps 

 I should have been quite unable to make any progress in 

 unravelling the stratigraphy of the district, as it would have 

 been beyond my skill to have constructed a map, in such difficult 

 country, whicli would have been of any use for detailed work.* 

 The town of Castlemaine lies on the chord of the arc which 

 forms the southern boundary of the horse-shoe-sbaped area of 

 granite extending from Elphinstone through Harcourt, to a few 

 miles south of Maldon. 



The Granite. 



The area occupied by granite is, in the main, gently undulating, 

 with a few scattered tors and bosses of rock. Occasionally it 

 rises into lofty hills, of which Mount Alexander (2435 feet) is 

 the highest point of the principal range. At the Harcourt 

 granite quarries a tine face is exposed. The rock, so well known 

 in Melbourne as a building stone, needs but little description. 

 Normally it is a grey, fairly tine grained rock. Occasionally, red 

 felspar occurs and gives it a pinkish tinge. Small patches of fine 

 grained rock with more abundant black mica occur having a very 

 definite outline. These are probably concretionary, as is stated 

 to be tlie case with similar patches occurring in Cornwall.t 

 Patches of very coarse grained rock occur at times, and on one 

 visit to the quarry I noticed traces of a gneissose structure. 

 Euritic dykes occur, but I have not seen any more than a few 

 inches in thickness. Druses or Vughs are rare at the quarry, 

 but one which occurred was lined with Ijeautiful ciystals of 

 what Mr. O. Rule, to whom I submitted i^pecimens, identiMed as 

 Stilbite and Albin, the latter mineral a variety of Apophyllite, 



'The mile posts as markeil on tlie quarter-sheets show a difference from Melbourne too 

 great by about six chains. Tliis is probably clue to a deviatiou made at Kyneton, and tlie 

 error will probably hold as far soutli as tliat township. 



t A. J. Phillips, Q. J. G. S., vol. xxxi., p. 1. 



