BS 
there can be no doubt that the calcareous travertine represents the 
much weathered condition of a former bed of shells and shelly 
detritus, and bearing this in mind together with the marginal posi- 
tion on lakes of most of the other travertine areas, it is not a great 
assum])tioii to make to suppose that they also were shell l)anks. 
^''ery little attention ap])ears to have been given by any observer to 
the calcareous deposits. i)rol)ably owing to exigences of travel and 
acceptance of the prevalent idea that they were merely travertines 
from l)asic rocks, but it seems to the writer that there is a very 
strong case made out for thinking that they are most probably 
of marine origin, and that they also will be found to lie fossili- 
ferous when well searched, d'liey will probably prove to yield the 
decisive evidence as to the truth or otherwise of the theory of a 
recent marine invasion of onr goldfields areas. 
The spongy to ])ulverulent, yet often also concretionary and 
nodular character of these travertines, and the frequent occur- 
rence with them of opalised matter, may easily he the result of 
subarid weathering of banks of shell sand. The thin coating of 
superficial limestone along the shore at Port lledland is of very 
similar character, and to a passing glance shows little or no sign 
of being formed from organic <letritus, yet with marine life 
swarming l)etween tide-levels on the shore close by, it can hardly 
be doubted that the limestones are <lerived from similar organic 
remains. Much of the betlded limestone near Ilopetoun, similarly, 
which is often jmetty distinctly stratified, has also a similar traver- 
tine-like character. In the railway cuttings lietween Cottesloe 
Beach and North Fremantle we see excellent sections showing a 
great amount of re-arrangement of the calcareous material l)y solu- 
tion and rei^recipitation along lines on which passage of wxiter 
through the mass has l)een jiossible. and there seems no good 
chemical reason to doubt that the transformation of shell sands into 
travertine-like deposits could easily result fr(jm sut)erficial weather- 
ing under the conditions of small i)rcci])itation and rapid evapora- 
tion ])revalcut on our fields. 'Phe fall of rain upon the porous 
material, and the subsequent withdrawal of the water from the 
soil by ca])illary attraction to surface and eva])oration. supply 
quite the ideal conditions for rai)id and extreme alteration of 
superficial calcareous beds. It is suggested that this rapiil weather- 
ing cf calcareous matter may l)e a very sufficient reason for the 
absence from the lake l)asins of any of the signs of marine life 
which would be ex])ected on the theory of their having been sul)- 
merged under the sea. 
s A L I X I T y nr w A T y. k s . 
The next question to which study of the lake areas leads us 
is that cf the degree and nature of the salinity of the natural 
waters found in the goldfields. This is a matter on which much 
light is likely to he thrown by the greatly hoped for publication at 
an early date by the Geological Survey of W.A. of all the numer- 
