KE. F. PITTMAN AND T. W. E. DAVID. CxXIX. 
to,’ and references to descriptions by various authors will 
be found in a paper by another of the authors.” The mound 
or mud springs are literally springs of liquid mud which by 
overflowing at the surface have gradually built up conical 
mounds, which in New South Wales are from a few feet to 
20 feet or more in diameter, and up to about 15 feet in 
height. (In South Australia, however, Mr. H. Y. L. Brown 
has described some mound springs which attain a maximum 
height of about 50 feet). The material of the mounds is 
formed of yellowish clay whitened in places by calcareous 
incrustations. A noteworthy feature is the occurrence in 
this clay of waterworn pebbles of quartz. [In Queensland 
in the mound springs described by Mr. E. Palmer (op. cit., 
p. 20) on the Lower Flinders River, the water is stated to 
evolve innumerable bubbles of carbonic acid]. As regards 
their distribution, an important characteristic is the fact 
that they usually occur in proximity to the junction between 
the older rocks and those of the artesian water-bearing 
series; in other words they are found adjacent to the edges 
of the basin or to the edges of the inliers of older rocks 
which at one time formed islands in the Triassic lake and 
Cretaceous seas. The experience has been that bores put 
down for artesian water near these mud springs have 
invariably yielded a much smaller flow than those situated 
at greater distances from the margin of the basin. It may 
also be mentioned that when bores have been sunk near 
mound springs, and have struck supplies of artesian water, 
as the result of the diminution of the pressure caused by 
the bore the water has ceased to flow from the adjoining 
mound springs. This has notably been the case at the 
Officer Brothers’ Bores at Kilara. In cases where obser- 
vations have been made as to the temperature of the liquid 
* The Mineral Resources of N.S, Wales, by E. F. Pittman, pp. 466 — 467. 
* Journ. Roy. Soc. N.S.W. 
