Western Victoria. 71 



It will be noticed that the height of the lava in the cliffs 

 just west of Cape Bridgewater is 150 feet. At Liddle's it is 

 only 70 feet, and at White's, only a mile away, it disappears 

 altogether under the limestone, wliicli, appearing at the Cape 

 as a layer a foot or so through, becomes 60 feet thick at 

 Liddle's, and is still deeper at White's. Therefore it appears 

 to me, that this cinder cone was breached on its south-west 

 side, at the extreme point of Cape Bridgewater, where the 

 wall of ash ends abruptly, leaving a chasm which was then 

 filled to its brim with lava flows. 



I set down the ages of these volcanic rocks as being 

 pliocene, pleistocene, and recent. At Portland the extremely 

 decomposed and oldest flows lie conformably upon the 

 Upper Miocene oyster beds. At Nelson Bay a lava bed is 

 intercalated between beds of limestone of pleistocene aofe, and 

 at the Bridgewater crater a great thickness of rock is crowned 

 by a little lava flow, already described, which looks as fi^esh 

 as if it had welled out but a few years ago, although the 

 lower flows dip under the pleistocene limestone. 



y. — The Pleistocene, or False-bedded Eolian 



Limestone. 



This is the most extensive formation exposed in this 

 district, and its position upon the western or windward side 

 of the promontory, challenges attention when we are con- 

 sidering its mode of origin. The rock is a moderately 

 compact breccia, composed of broken marine organisms, 

 mainly shells, cemented together by a calcareous paste, which 

 is coloured by iron oxides. These latter give to the strata 

 various shades of red, yellow, and grey. The stone appears 

 to harden with exposure, and this probably is the result of 

 the more complete solidification of the external portions, by 

 the infilling of all the interstices of that part of the breccia, 

 with travertine, supplied by the soakage through it of rain 

 and spray, carrying carbonic acid. 



The composition of the rock seems to vary slightly from 

 point to point, for Mr. Woods describes it as containing 

 lime, magnesia, and silica, with traces of sesqui-oxide of iron, 

 and sulphate of lime, while Mr. Dennant says that it is 

 a carbonate of lime, with four per cent, of silica. 



The formation is composed of beds from 10 to 20 feet 

 thick, and these are disposed horizontally. They are all 



