392 PEOCEEDIN-GS OP THE GEOLOGICAL SOCIETY. [April 5, 



could find fossils except in the first few inclies of loam. After a 

 careful examination of all the specimens, I could not detect one 

 which does not belong to the Hamilton beds. The species prevailing 

 are the same, but the Nucula is the most common. The Gyprcea 

 eximia appears to have been common too, and also some of the corals 

 enumerated below, but in other respects the specimens are too broken, 

 to be pronounced upon without long and careful examination. In 

 fresh broken pebbles the Ampliistegina vulgaris can be readily de- 

 tected in the usual abundance. It is a curious fact that though the 

 ferruginous gravel is distributed over many miles of the neighbouring 

 country, this neighbourhood is the only one in which I have found 

 fossils among its pebbles. The same kind of gravel has been noticed 

 throughout a great portion of the continent of Australia, almost, in 

 fact, wherever an explorer has penetrated. It would be interesting 

 to ascertain whether it was all of the same geological age. As yet 

 we can only speculate on the subject ; but as the continent is gene- 

 rally at so uniform a level, even a guess may be founded on strong 

 probability. It is certain that the formation is widely distributed. 

 It has been found in Hobarton, Tasmania, at Geelong, at Hamilton, 

 and at Harrow, making an extent of at least six degrees of latitude 

 and five of longitude. Add to this the fact that the fossils have 

 strong Philippine affinities, and thence we may infer that the whole 

 continent of Australia was then submerged, leaving a clear sea to 

 the equator. Under ordinary circumstances we might look for simi- 

 lar deposits in remote parts of Australia, and it is just possible that 

 the ferruginous gravel which is so widely distributed may belong to 

 the same geological age. 



The Hamilton beds and the Mount Gambier limestones have been 

 regarded as belonging to the same age, yet I have now little doubt 

 that this opinion must be modified. In the first place the character 

 of each deposit is very different. The Hamilton beds are clays full 

 of large fossil shells, while at Mount Gambier the formation is hard 

 and rocky, and even in its most friable state has at least the consist- 

 ence of chalk. It has also flints which are never found in Hamilton, 

 or Geelong. Then, again, the fossil contents of the beds could not be 

 more diflferent. At Mount Gambier the limestone teems with Bryo- 

 zoa, but rarely contains a perfect shell. If they do occur they are 

 confined to three or four genera, such as Terehratida (which is the 

 only common form), Pecten, Spondylus, and Anomm. EcMnidce are 

 also common, particularly such genera as Ecliinolampus and Spa- 

 tangus. The stone where such fossils do not occur is made up of 

 a kind of limestone-paste, with Foraminifera and broken Bryozoa 

 abounding. The Foraminifera are such as exist now at a depth of 

 from 200 to 300 fathoms, and therefore the Bryozoa may have been 

 derived from a distance. In fact the deposit seems like a series of 

 layers of deep-sea mud tranquilly deposited in the bottom of the 

 ocean or brought by slow degrees from a distance. 



In scarely one of these respects does the Hamilton deposit resemble 

 the hmestone. Bryozoa are common, but do not, as at Mount Gam- 

 bier, make up the principal part of the deposit. EcJiinidce are rare, 

 and so are Terebratulce, at least in comparison with the numbers 



