169 
THE GEELONG NATURALIST. ~~ 
may at least be examined and recorded. In deposits of this 
nature, which cannot be said to be highly fossiliferous, every 
fresh record is of the utmost value. 
The Age of the beds mentioned is a somewhat difficult 
problem to fix definitely. Professor Sir F. McCoy is of the 
opinion that they are of Newer Pliocene Age, and correspond 
to other superficial deposits in many parts of the colony, 
which contain Diprotodon, &c., remains. In many European 
works dealing with this characteristic Australian fauna, the 
beds are spoken of as Pleistocene. 
In conclusion, I need hardly say that I shall be most 
happy at any time to examine fossils from these deposits, and 
I hope the Club will do their best to collect additional 
material, and so increase the number of fossils known from 
their district. 
THE SAND-DUNES OF THE COAST. 
By G. B. PRITCHARD. 
Tue first question that presents itself to us in dealing with 
this subject is:—What is sand? Sand may be defined as a 
loose incoherent mass of minute fragments or grains, each of 
which has a definite mineral composition of its own. Thus 
we may have sands made up of minute to coarse grains of 
quartz, which we would call a silicious or quartzose sand; 
this being by far the commonest kind of sand, it is, perhaps, 
the usual practice simply to call it ** Sand,” without indicating 
.its chemical composition. We may, however, have sands 
entirely made up of grains of carbonate of lime, and this 
would be called a calcareous sand. Such would result from 
the breaking and pounding up of the shells of marine molluscs, 
polyzoa, echinoderm tests and spines, corals, calcareous algz. 
&c., by the energetic action of the sea so easily observed 
along any coastline. 
Iron sands are not uncommon, made up of grains of the 
various oxides of iron, such as limonite, hematite, magnetite, 
or ilmenite (titaniferous iron), the latter frequently being 
what is so well known to alluvial miners as “ black sand." 
Gem sands are also well known, being essentially made 
up of such gems as zircons, garnets, pleonastes, sapphires, 
-rubies and topazes. Sands of other compositions are known, 
but these will suffice for our present purpose. 
Now, in dealing with the sand dunes of any coast, it 
must not be forgotten that the chemical composition of the 
sand constituting the dunes will depend mainly upon the 
nature of the rocks subjected to marine erosion, and frequently 
also upon the abundance of certain kinds of marine life 
inhabiting the littoral zone. 
