132 Proceedings of the Royal Society of Victoria. 



Surface soil ----- 



Gravel ------ 



cc rCalcareous sandy clay with two or 

 three bands of limestone 



Band of sandy clay with ironstone 

 gravel ----- 



Calcareous sandy clay with lime- 

 stone full of casts of eocene 

 fossils ----- 



Alluvium of river bank - 



Total - 54 



The Tambo here is estimated to be onl)' about four feet above 

 sea level, though it is still at a considerable distance from its 

 mouth at lake Victoria. The tide reaches at least thus far up 

 the river, its marks l)eing visible at the Punt. 



Though the Swan Reach section is not, as will be shown later 

 on, the most westerly outci'op of the miocene strata of the area, 

 the deposits appear to thin out in that direction, whereas to the 

 east they make strongly, and at Jemmy's Point, with those 

 portions reckoned only which are certainly fossiliferous, a thick- 

 ness of at least tifty or sixty feet is apparent. It marks also 

 almost the noi'thern })Oundary of the miocene, since as the Tambo 

 is followed up for a short distance, the river cliffs which consist 

 of hard limestone (the so-called polyzoal rock), are of eocene age. 

 They form a part of, and are probably continuous with, the 

 Bairnsdale limestones, which are, as is well known, characteristic- 

 ally eocene. 



That a junction of the miocene and eocene strata is presented 

 in the Swan Reach section is clear enough, and the only difficulty 

 is as to how the intermingling of the shells in the manner 

 described was brought about. Our theory concerning the section 

 is that it represents a re-made bed, the eroded surface of eocene 

 strata having formed the floor of the miocene beach. The lime- 

 stone blocks containing casts of eocene fossils which lie beneath 

 the ferruginous band, are probably /;/ sid/, while the easts and 

 worn shells, which are mixed with well preserved miocene forms 

 higher up, may be regaided as derived from the waste of the 

 ancient shore line. The two eocene bivalves Pecten vnh/eusis and 



