PROCEEDINGS OF SECTION C. 211 



A little to the west of the Darebiu Creek there is a fairly well- 

 marked synclinal, but no Yeringian fossils have yet been recorded from 

 that area. The highly crumpled series from Heidelberg to the Plenty 

 ■River exhibits some minor synclines, but not on so large a scale as 

 to have enclosed and protected the overlying Yeringian series. Beyond 

 Warrandyte, to the east, the Silurian rocks are again thrown into 

 extensive folds, which fortunately have preserved, together with the 

 senkungsfeld interference, a remarkable series of Yeringian strata. An 

 upper series of fossiliferous brown mudstones and sandstones are 

 found in quarries south-east of Wonga Park, and in the immediate 

 neighbourhood of Lilydale. These mudstones are extremely rich in 

 brachiopods, corals, and trilobites, and the general facies is that of the 

 Weulock limestone and the Lower Ludlow shales. The famous quarry 

 at Lilydale is situated in a band of limestone, which is tilted at a high 

 angle (35-50°), and consists largely of corals (Favosites, Heliolites), 

 stromatoporoids (Clathrodictyon, Actinostroma), gasteropods (Mur- 

 chisonia, Euomphalus, Cyclonema), and ostracoda (Primitia, Bytho- 

 oypris). These fossils resemble, generally speaking, those found in the 

 Wenlock limestone of England. The Cave Hill or Lilydale limestone 

 is apparently represented farther to the east by the impure limestone 

 of Seville ; whilst the fossiliferous Yeringian mudstones round Lilydale 

 are again in evidence at the Yarra Flats and View Hill Creek. Near 

 Killara, at the junction of the Woori Yallock and Yarra Rivers, these 

 beds were determined by McCoy as of Bala age ; but, judging by an 

 extended examination of its fauna, they appear to be identical with 

 the fossiliferous mudstones in the neighbourhood of Lilydale. 



Both limestones and mudstones of Yeringian age are well developed 

 in many Gippsland localities ; and a striking feature of their strati- 

 graphy is their constant unconformable association with immediately 

 underlying Upper Ordovician slates. This points either to a recession 

 of the Silurian sea during Melbournian times, or to a more rapid sinking 

 of the Silurian basin in the latter period, resulting in a distinct overlap 

 of the strata. At Walhalla, a bed of limestone occurs, full of corals, 

 many of which are similar to those of Lilydale, although some are 

 peculiar to the locality. The same may be said of the Waratah Bay 

 limestone, which is also Yeringian, but contains an aberrant species of 

 Tryplasma (? T. murrayi, Eth. fil.) peculiar to this bed.* At Loyola, 

 near Mansfield, beds of limestone are found associated with mudstones, 

 each containing its own particular Yeringian facies ; that is, chiefly 

 corals in the former and brachiopods in the latter. The Tyer's River 

 and the Mitta Mitta limestones are also of Yeringian age, and are 

 largely of crinoidal and coral origin. In the former an interesting and 



• Etheridge ('99), p, 32, p!. A, flgs. 1-S ; also, Id. ('07), p. 93, PI. XXVIII. 



