Rocks near Heathcofe. '.i 1 5 



entered on field work in the district with the intention of 

 examinin<r the field evidence as closely as the time at my dis- 

 posal would permit. My attention was larirely directed to the 

 relations of the i2:neous rocks to the Ordovicians, and to the 

 black cherts, and I paid particular attention to the areas above 

 cited, and notably the occurrences at S. Heathcote, just north 

 of Photograph Knob, and now present the results of my investi- 

 gations. 



4. — Relations of the Igneous Rocks to the Silurian Series. 



S. Heathcote. — Behind and for some distance to the north-west 

 of tho S. Heathcote Hotel, silicified and chertified diabase, and in 

 places a mixed seh\ynite and carbonate rock occurs, forming the 

 western boundary of the Mclvor Creek. The Silurian rocks, 

 mainly sandstones and quartzites, outcrop on the opposite side of 

 the creek, and just below the hotel are see^n in section in the 

 stream, near where scheelite was found some years ago. N<j actual 

 contact, howver, could be seen. 



Heathcote. — Within the limits of the township the relations 

 between the two series are everjnvhere ol)scui-ed by the recent 

 alluvium deposited by the ^TcTvor Creek. 



JVear the ^' selwi/nite" Outcrop. — This occurs about 2^ miles 

 north of the township, on the MuiTay Road, on the west side, 

 and just north of the junction of the road running X.W. towards 

 Derrinal. Selwyn described this substance as '' in a vein in the 

 Silurian."' There can, however, be no doubt that it is within 

 tho diabase area, although very close to the junction, as diabase 

 in situ occurs in a small g:ully on the east side of the road. 

 The seh\ynite appears to be a peculiar modification of the dia- 

 base. Near here Prof. Gregory states that .sections of the basal 

 Silurian rocks contained fragments of diabase. I have had sec- 

 tions of some of these rocks made, and there occurs in some of 

 them small iron-stained areas which may very likely be decom- 

 posed diabase fragments, although I am unable, owing to their 

 iron-stained character, to be certain of their nature. 



About 3 Miles jV. of' selii'ijnite Outcrop. — A road joining the 

 Murray road and running between paddocka 3m and 3j towards 

 the isolated diabase mass in Tranters paddock, Knowsley East, 



