10 
SHELL SAND IN THE WARRNAMBOOL DISTRICT. 
By D. J. Mahony, M.Sc., F.G.S., Petrologist. 
Between Wavrnambool and Port Fairy, a distance of about 15 miles, the- 
coast is fringed by extensive sand-dunes,'which vary in width from 100 yards- 
to a quarter of a mile or more, and rise to an average height of about 50 feet. 
Very probably they extend beyond the places mentioned. These dunes are 
formed of loose sand, which moves with every breeze, and they are now devoid 
of natural vegetation, though there are signs that at one time a part, at least, 
was covered with tea-tree scrub. A good deal of marram grass has been 
planted to prevent the sand from shifting and encroaching on the rich volcanic 
soils, but the available evidence indicates that there has been very little 
movement since the country was occupied. 
The important feature about these dunes is that in many places they 
consist almost entirely of small pieces of sea shells, which have been broken 
up by the waves and then blown by the wind to their present position. This 
sand has, indeed, the composition of a fairly pure limestone. An average 
sample gave the following results on analysis :— 
CaC0 3 
• • • 
per cent. 
8625 
Insol. (SiCU)--. 
• • • 
• • • 
5-10 
A! 2 O 3 
• • • 
• ■ « 
057 
Fe 2 03 
... 
• • • 
0-87 
MgCOs 
• • • 
. • • 
6-64 
NaCl 
... 
... 
present 
P#5 
. . . 
t •>! 
do. 
H 2 0 
... 
• • • 
0-41 
99*84% 
CIO. 
The 6.64 per cent, of magnesium carbonate is higher than might be 
expected. 
There is here, then, a deposit -of many millions of tons of finely-divided 
limestone, apparently in a form suitable for agricultural purposes. The 
value of crushed limestone as a fertilizer has been the subject of elaborate 
investigation by the United States Department of Agriculture for the past 
25 years, and its use, when applied to certain soils, has been abundantly 
proved. In a report (Farmer’s Bulletin No. XL., 1907), it is stated that 
calcium carbonate (limestone) gave decidedly better results than caustic 
lime (quicklime), and that the application of shell marl produced more grain 
and fodder than either stone lime or oyster-shell lime ; and that it is cheaper 
and much more effective than gypsum. In certain of the States the railway 
companies carry limestone at very low rates, because it is realized that the 
general prosperity of these companies is bound up with the fertility of tlie soil. 
The beneficial action of limestone upon soils may be chemical or physical, 
or both. The chemical action consists directly in supplying lime, in which 
many soils are deficient, or, indirectly, in neutralizing the acidity ; the physical 
action takes the form of keeping the soil open and porous. In Victoria the 
agricultural value of many good soils is handicapped by their acidity, 
especially in reclaimed swamps or districts where cattle have been grazed 
fcrr many years, and in irrigated areas the pores of the soil tend to become 
clogged, so that a more or less impervious layer is formed ; in these cases the 
application of limestone should be most beneficial, but hitherto the high 
cost of limestone and lime has prevented its extensive use. 
The shell sand of Warrnambool is close to the railway, and could be 
reached by sidings. Should the demand warrant the use of steam shovels,. 
* 
