Geological Structure about Mornington. 39 



along the beach floor. We then find basalt, and under it on the 

 beach olive shales with Angiopteridium spathulatum (syn. 

 Taeniopteris daintreei) and Thinnfeldia odontopteroides. Abut- 

 ting on these Jurassic beds is the granitic rock, capped and 

 masked by ferruginous sands. The fact that the Jurassic series 

 owes its position to being faulted down against the plutonic rock 

 was, as mentioned above, long ago stated by Selwyn, and a mile 

 and a half inland the latter rock still rises to a height of over 

 500 feet. 



Balcombe's Bay. 



Near the northern end of the shallow indentation known as 

 Balcombe's Bay is the well-known fossiliferous outcrop of Eocene 

 clays and limestones.^ 



The limestone strings and bands were formerly used for making 

 cement, and the ruins of the works are still to be seen. As is 

 shown by the limestone bands, the clays are somewhat disturbed ; 

 in one place, north of the cement works, the dip is — E., 25° N, 

 at 16°, but changes rapidly in amount and direction, and occa- 

 sional sigmoidal curvature of the outcrop, shows the existence of 

 slight contortion, with a dip of from 15° to 20°. Close to the 

 cement works, the beds dip steadily towards the south-west. If 

 this dip held, they would pass under the extension of the basalt 

 which forms the base of the small point to the south ; but, 

 judging by what we see elsewhere, they do not. 



On rounding this point, the character of the beds is entirely 

 changed, and from sea level to a few feet above high- water mai^k, 

 we find grits and light conglomerates, with pebbles of quartz and 

 slate, and interspersed with bands of lignite and carbonised tree- 

 trunks. Dicotyledonous leaves are plentiful, and no trace of 

 Jurassic plants is to be seen. The strata are fairly horizontal, 

 but current-bedded. Over these beds, and not apparently sepa- 

 rable by an unconformity from them, occurs a series of strata 

 of difiereut character. These are lavender-coloured and yellow 

 sandy clays, with a considerable amount of gypsum and copia- 



1 Like many of our longcer known greological localities, which were found when geo- 

 graphical names were not so thickly scattered as they are now, this outcrop is known by 

 many designations, such as Schnapper Point, Mornington, Mount Martha, or even 

 Hobson's Bay, though the Bay is thirty miles away. Probably " near the mouth of the 

 River Yarra " also refers to this spot, and was near enough when it was written. 



