136 



In the following descriptions, the major formations are 

 taken in descending order from the surface. 



Division 1. 



RECENT SURFACE FORMATION. 



Travertine, with more or less blown sand, forms a surface 

 layer. The travertine is the usual surface form developed 

 under the conditions of a semi-arid climate. In some parts 

 of the field, the travertine sits directly upon the Ostrea lime- 

 stone, and is little more than an addition to and modification 

 of it. Elsewhere, sandy beds intervene which may or may 

 not belong to the marine series below. 



« 



Division^ 2. 



A KALIMNAN (lOWER PLIOCENE) OYSTER BED. 



This is a hard marine limestone, usually buff-coloured. 



This rock is what may be termed a "rags tone," or roughly 



fracturing limestone, filled with oyster shells and pectens. 



It would appear from the res'ults of borings that this bed is 



not continuous over the field. In many cases, however, it 



is undoubtedly included with the surface travertine in the 



one entry. The fossils determined from this horizon are: — 



Pelecypoda — Ostrea arenicola, Tate, a smooth upper 



valve; 0. sturtiana, Tate, probably the commonest 



fossil in this bed; Pecten antiaustralis , Tate, rare; 



P. palmipes, Tate, a fragment only; Spondylus 



arenicola, Tate, a restricted Aldingan species, rare. 



Pisces — Isurics hastalis, Agassiz, sp. (tooth). This fossil 

 is rather worn, but the outline leaves no doubt of its 

 identity. A common Victorian Kalimnan fossil. 



Embedded in this limestone small pebbles of white quartz 

 and other rocks are occasionally met with. Of the latter 

 the following were collected: — A water-worn pebble, 3 in. 

 in length, of a rock resembling a mica granulite; several 

 chips of slate up to 2 in. in length ; and two pieces of basalt, 

 one water- worn, the other partly faceted. 



The latter basalt specimen measures about 4 in. by 2 in. 

 It is a grey rock with open steam holes, the vesicles being 

 drawn out by flow. In microscopic section, laths of labra- 

 dorite felspar are noted to be the dominant feature. A flow 

 arrangement of the felspars around the steam holes is evident. 

 A large corroded fragment of plagioclase exhibiting poly- 

 synthetic twinning is also to be seen. A small amount of 

 interstitial pyroxene is still visible. A considerable quantity 

 of secondary serpentine is present and appears to be chiefly 



