Tertiaries in the Neighbourhood of Melbourne. 213 



and near Batesford where the granite probably underlies at no 

 great depth. 



There is one feature in common to all these cases, and that is 

 the comparative imperviousness of the bed rock, whether it be 

 porphyry, basalt, decomposed ash or sedimentary clay. The 

 typical polyzoal limestone is very open and porous, and it 

 consequently offers a free channel to the passage of underground 

 waters, which would accumulate in them in such localities and 

 thus bring about the solution and redeposition of the calcareous 

 matter and so destroy in places all evidence of organic contents. 

 Mr. A. \V. Howitt (18, p. 209), mentions a similar alteration in 

 Devonian limestone, which a previous writer had explained as 

 due to the intrusion of an igneous rock. Mr. Howitt shows that 

 the limestone in question was laid down on a shingly bottom and 

 ascribes the alteration to the infiltration of silica set free during 

 the decomposition of the porphyry beneath. 



In the road cutting on the opposite side of the valley the 

 junction of the tertiary beds with the underlying volcanic rock 

 is well displayed. The upper surface of the latter is very uneven 

 and the rock is quite wackenitic. Immediately resting on it is 

 a bed of chocolate-coloured grit about five feet in thickness 

 which yielded us a few fossil casts. 



We found Haliotis ncevosoides, M'Coy, and a shark's tooth, 

 possibly Lainna. 



This bed is overlain by about four feet of fine grained yellow 

 sandstones which are current-bedded. Over this again come thin 

 beds of water-worn gravel. Over a wide area in this locality 

 overlying the fossiliferous beds we have a bed of sandstone 

 and gravel, which in some places is loose and incoherent, and in 

 others is cemented so as to be a hard white quartzite. The finer 

 varieties look like porcelain. Of the equivalents of the beds 

 over the fossiliferous grits we are uncertain, as we have not been 

 able to get a junction between the two sets. We, however, class 

 them, provisionally, with the Miocene series till further evidence 

 be forthcoming. 

 Foraminfera. 



Echinodermata. Spines and cidaroid plates. 

 Polyzoa. 



