Geology of Castleuiaine, &c., with List of Minerals. OH 



House, below Patterson Bridge. The surface of the rock, an 

 olive slate, was closely covered with tiat oval depressions about 

 one-fourth of an inch in diameter. In some cases, on these 

 depressions were seated small cones about one-eighth inch in 

 height, of a whitish coloui', finely transversely striated and longi- 

 tudinally more deeply goo\ed. and having somewhat the appear- 

 ance of sessile barnacles. The flat bases were downwards, and 

 on the cleavage pl8nes. The apices of the cones were embedded 

 in a softer clay, and as no trace of obverse cones was visible the 

 name cone-in-cone will not apply. The structure is undoubtedly 

 not organic, and Mr. Newberry, to whom I sent a specimen, 

 submitted it to Mr. Howitt, who informs me that he considers it 

 to be of a concretionary natvire. I have seen several less perfect 

 examples, where the cone bases if not carefully examined would 

 perhaps be considered rain-prints, and from the cleavage making 

 the depressions deeper on one side than on the other the direction 

 of the wind would doubtless be inferred. 



Some of the blue and grey slates are thickly marked with red 

 oval patches, mainly on the cleavage planes. Frequently a small 

 speck of limonite in the centre shows that a gi-ain of pyrites 

 has yielded the colouring matter which has spread out through 

 the I'ock in the easiest direction. tSmall oval films of pyrites 

 were also observed in slates at the Devonshire Mine, which on 

 decomposition would yield the same appearance. 



Limestones are apparently absent, though Mr. Dunn* records 

 a narrow band of black limestone from similar rocks at Bendigo. 

 The pi'esence of lime in the beds, is shown by the occurrence of 

 strings and patches of magnesian limestone, in joints of the slates 

 near Patterson Bridge, and at the south end of the Barker's 

 Creek slate quarry. The frequent occurrence of calcite and allied 

 lime-bearing minerals in the quartz veins points to a similar 

 conclusion. 



Slaty cleavage, as before mentioned, is strongly developed all 

 over the district, and has a strike coincident with that of the 

 beds. Over the western part of the field, the dip of the cleavage 

 is about 80° to the westward, but whether this direction holds 

 for the Maldon side of the district, I cannot say. In the railway 

 cutting, on the Elphinstone side of the tunnel, the quarter-sheet 



* Op. cit. 



