GcoliKjij of the Diamonil ('reek Area. ■>2', 



4.— Stratigraphy. 



The follo\viiii( formations are represented in tlie area: — - 



-r, , . I Silurian sediments. 



Jralaeozoic ; ■ , , , 



i ? Devonian acid dykes. 



,„ . , liiver or lacustrine jfi-avels, sands, etc. 



tertiary ' 



( Basalts. 



Recent alluvium. 

 The oldest member of the series consists of interbedded sandstones, 

 mudstones and shales, containing considerable amounts of mus- 

 covite, and varying greatly in colour and coarseness. Occasional 

 bands of quartzite and slate occur at intervals, and a series of 

 grits and conglomerates has been described from Warrandyte.i 

 i-i^rom the various lithological and microscopical characters of these 

 rocks they appear to be entirely marine, and to have been laid 

 down mostly under shallow water conditions. Cf Jutson. c, p. 530. 

 Some of the sandstones in the west of the area show good current 

 bedding on a small scale, one section in particular from Dry 

 Creek showed this very well. No extensive palaeontological work 

 was attempted, mainly owing to lack of time. An interesting find, 

 however, was the discovery of graptolites in black pyritic slates 

 from the Diamond Creek mine. Dr. Hall has kindly examined 

 these, and he has informed me that both climacograptus and diplo- 

 graptus are represented, but he says there was not sufficient evi- 

 dence to enable their precise age to be determined. It may be of 

 interest to note that climacograptus and diplograptus both range 

 into the lowest member of the silurian, namely, the llandovery 

 series in England; but as fas as the writer is aware, neither have 

 been definitely proved to exist in the silurian in Victoria. It 

 seems clear, therefore, that the beds near Diamond Creek are at 

 least melbournian or older in age, and probably older than Jutson 

 was inclined to regard them. It might be noted in this connection 

 that Selwyn regarded the beds of the Templestowe anticline, i.e., the 

 anticline near Diamond Creek, as the oldest of the scries. Two 

 or three other fossils were found, and for the examination of them 

 the writer is indebted to Mr. Chapman. The first fossil is from 

 section 7, allotment 3, in the east of the area, and is a trachy- 

 derma, which Mr. Chapman informs me occurs botli in melbournian 

 and in the yeringian, and so is of no diagnostic value. The other 

 fossil examined was from the Plenty River just below the aqueduct. 



1 Jutson. c, p. 530. 



