The Heatlicot'ian. 149 



and the students of the Geological Department of the Melbourne 

 University. Our joint examination of the country showed that 

 the explanation was well founded. 



Heathcote is a straggling township extended for about three 

 miles along the Bendigo Road, in the broad valley of Mclvor 

 Creek. It is situated seventy-four miles northward from 

 Melbourne. Along the floor of the Heathcote Valley, and 

 upon its south-western slope are numerous exposures of a 

 series of igneous rocks, which can be divided into an acid and a 

 basic series. In close contact with these igneous rocks are some 

 narrow belts of rocks which are clearly metamorphic sediments. 

 These metamorphic and igneous rocks extend from the head of 

 Mclvor Creek, along a bold curve to the north-west ; bending to 

 the north, they are continued on the floor of the valley to the 

 west of Mount Ida, whence they gradually rise and form the long 

 Colbinabbin Range. The rocks of these metamorphic and diabase 

 series extend along this line, with occasional slight interruption, 

 for about thirty miles. On the north-eastern side of this line 

 the rocks are quartzites of silurian age. On the outer side of 

 the curve to the west and south-west the rocks are slates, 

 quartzites, and sandstones of ordovician age. 



II. — Previous Litehaturk. 



The literature begins in 18G6 with Selwyn's Geological Sketch 

 of the Colony of Victoria,^ in which th,e rocks of this line are 

 marked simply as trap, and they are described (p. 172) as dykes. 

 More precise information was given by Selwyn in 1868 in his 

 " Descriptive Catalogue of the Rock Specimens and Minerals in 

 the National Museum, Melbourne" (p. IG), in which the rocks 

 from Mount Camel, the highest peak in the Colbinabbin Range, 

 were determined as diabase ; but in the same work, in the list of 

 errata, the name was changed to diorite, owing to the indenti- 

 tication of the ferromagnesian constituent as an amphibole 

 instead of a pyroxene. A material described as a mineral under 

 the name of selwynite," which occurs in these rocks four miles 

 north of Heathcote was described as in "a vein in the upper 



1 A. R. C. Selwjn: Official Record Iiitercol. Exhib., Austral., 1866-1867, pp. 147-227. 



2 Ibid., p. 18. 



