of the Buchan District. 33 



or melaphyrs of older. I have at present no data to decide 

 this question* 



I have shown reasons for believing that the intrusive 

 igneous rocks at the Murendel, and along the track thence to 

 the Snowy River, as well as the contemporaneous rocks at the 

 Snowy River itself, are all varieties of Diabase. To this 

 must be added similar rocks at Back Creek, and on the 

 eastern side of the Buchan River, near that place. It is 

 necessary to enquire now, what are the relations of these 

 igneous rocks to the great group of formations, called the 

 Buchan beds, and among which they are found ? 



At Buchan, Murendel, Butcher's Creek, Rodger's Creek, 

 the Snowy River, and Gellingall, the characteristics of these 

 Buchan beds are always the same. I have found the group to 

 consist invariably of two well-marked divisions.*)" A lower 

 series (Lower Buchan beds) of from four hundred to five hun- 

 dred feet in thickness, almost wholly of fragments of felsitic 

 and, more rarely, sedimentary rocks, with interposed felsite 

 sheets ; the upper series (Upper Buchan beds), of from 

 750 to 1000 feet in thickness, consisting almost wholly of 

 marine limestones, rich in remains of corals, mollusca, and 

 placodermatous fish of Middle Devonian age. The excep- 

 tion to this completely calcareous nature is in the passage- 

 beds at the base of the series, in which the felsitic and 

 calcareous characters are commingled, decreasing as to the 

 former in passing upwards, until, at heights varying from 

 (say) ten to fifty feet, the beds are the purely marine lime- 

 stones, characteristic of the Upper Buchan beds. 



The two groups are not discordant to each other, the dis- 

 tinction being in the nature of the materials of which they 

 are composed. In addition to the particulars relating to the 

 contact of the Upper and Lower Buchan beds, which I have 

 given in the previous papers quoted, I now give the 

 following : — 



I have found the contact of the limestone and fragmental beds 

 to be well marked near the Murendel mine, and on tracing 

 the beds further up the Murendel River, it became evident 



* Whilst this paper has been going through the press, I have had an 

 opportunity of again visiting this locality. A careful examination has 

 satisfied me that the olivine-bearing rocks are. in fact, part of the same group 

 which here generally and immediately underlies the marine limestones. 

 Here, as elsewhere, the beds are some crystalline and some fragmental. I 

 reserve fuller particulars for a future communication. 



f Progress Report Geological Survey of Victoria, Part V., p. 117. 



