^Qi^s'] Chapman, Victorian Fossiliferous Limestones. 139 



VICTORIAN FOSSILIFEROUS LIMESTONES AND THEIR 

 CORRELATIVES IN OTHER LANDS. 



Synopsis of an Illustrated Lecture 



By F. Chapman, A.L.S., Palaeontologist to the National Museum, 



Melbourne. 



{Delivered before Field Naturalists' Club of Victoria, Sth Sept., 191 3.) 



Limestones are amongst the most important rocks which come 

 under the notice of those who study fossils. Organic remains 

 found in limestones are, as a rule, well preserved as compared 

 with those found in rocks in which the sealing-up process has 

 been protracted over a more or less lengthy period. The clays 

 and marls may be considered next in importance, for they 

 also usually contain fossil remains in good condition, especially 

 when of the close-textured kinds. Incoherent marl-rocks and 

 sandstones, on the other hand, cannot be compared with the 

 limestones in their excellently preserved animal remains, 

 including pre-eminently the corals and foraminifera. The 

 group of the mollusca, however, may be quoted as an exception, 

 for the marls are perhaps more suitable for the preservation 

 of this type of organism in relation to their original shell- 

 structure than even the limestones. 



Victoria is particularly well favoured in the occurrence of 

 large deposits of limestone both of Palaeozoic (earliest) and 

 Cainozoic (latest) periods. The rocks of the Mesozoic (middle) 

 period, however, are practically wanting in this State, but are 

 represented by the Jurassic limestones of Western Australia, 

 the Lower Cretaceous of Queensland, New South Wales, and 

 South Australia, as well as by the Chalk of Gin Gin, in Western 

 Austraha. 



In treating of this subject from the standpoint of the fossil 

 contents, the youngest series, being most famihar to us, may 

 be taken first in order, and limestones forming at the present 

 time make an interesting study. Young sand-dunes are often 

 seen along the coast of Victoria, only a few feet in height, and 

 upon these are generally found growing such plants as the 

 sand-binding grasses and salt-loving shrubs. These plants, by 

 their spreading and fibrous roots, bind the shifting sand-mounds 

 and prevent their removal by the wind. Sometimes these dunes 

 are as much as 120 feet high, as were seen at Torquay about 

 eight years ago, but which have been reduced during the lapse 

 of six years to 40 feet. The dune-sand, being largely composed 

 of comminuted shells, is continually undergoing solution by 

 percolating rain-water containing CO 2, the mineral matter being 

 re-deposited around the underlying grains. Thus the mass is 

 gradually transformed into a hard limestone such as is used at 



