244 Frederick Cltcqyman : 



Episodes in the Formation of the Beds of the Great Biylit Area. 



In i^re-Mioceiie times the area abutting on the Cretaceous of 

 the Lake Eyre district to tlie north-west, to Charh)tte Waters on 

 the north, to Albany, on the west, and to the Adehiide Ph\ins on 

 the east,. and far to the soutli on what is now the Southern Ocean, 

 was probably dominated, by an estuarine or generally base-levelled 

 country. This area also extended through the Riverina as far as 

 Wagga, in Xew South Wales, and occupied a large part of the 

 Wimmera and Mallee districts of A'ictoria. The underlying 

 (fundamental) I'ocks of this area consist mainly of granite," 

 chloritic slate, felspathic quartzites, slaty rocks and sandstones, 

 .all excepting the granite jJossibly referable either to the Ordo- 

 vician, Cambrian or metamorphic series, including Algonkian. 

 Tlie deposits laid down on these basal rocks were river, estuarine, 

 swamp and lake accumulations, consisting of sands and clays with 

 carbonaceous and lignitic material. 



Following the deposition of these ]>eds, whicli, by the way. were 

 "not uniformly spread over the entire area mentioned, there were 

 occasional oscillations which brought them below sea-level, causing 

 an interstratification of marine beds with the terrestrial. Later, 

 the oscillations ended in a steady to (|uick downward movement 

 until a depth of at least 100 fathoms l>elow sea-level was reached. 

 In this sea-bed a rich deposit of calcareous mud was formed, filled 

 with debris of polyzoa. echinoids, mollusca and foraminifera. 

 These beds can lie referred to the Janjukian series of Victoria, and 

 are honiotaxial with the Miocene of Europe. 



In Lower Pliocene times (Kalimnan series) the sea-bed ro.'-e to 

 witliin a few fathoms of the suiface. with fine sandy deposits, 

 upon which flourished molluscs as Ostrea. Xafiea, Tvrritella and 

 the sea-urchin. TMganvm, amongst many otlier organisms. In 

 places there were huge oyster banks, and in the more rocky parts 

 vast deposits of mollusca peculiar to such conditions, as Mi/tihis, 

 Borneo, Veriernp's, Area, CneidJaea and GJi/cimeris, a few species 

 of which facies are still living. Possijjly a part of tlie Miocene 

 limestone of which the fauna is here discussed, may have per- 

 sisted into the Lower Pliocene, as evidently a few forms, such as 

 TelUno cf. olhinelloides and Loqonnm. seem to indicate. 



In the later period of the Pliocene this sea-bed again deepened, 

 and a shell deposit with many existing species was laid down. 



7 Tn the All)any district these older limestones = Plaiitanenet Beds) liave been sliowii 

 "by J. T. .Intsoii and E. S. Simpson (Journ. and Proo. Hoy. Soc. W. Australia, Vol. II., 

 1917, p. 48) to have been laid down on the fjranite. 



