340 
PROCEEDINGS OF SECTION C. 
sea. Numerous well-known instances of fresh -water springs rising 
out of the beach sands, and even in the bottom of the sea, show that 
even a feeble pressure at the back of an underground stream of fresh 
water is sufficient to keep out the salt water. 
It has already been mentioned that the Desert Sandstone covers 
a large area of the outcrop of the Blythesdale beds. Although the 
former is less bibulous than the latter, it is still very absorbent. Mr. 
Tolson’s remarks about 10 inches of rain having fallen on this forma- 
tion without making the streams run arc very much to the point, and 
I can confirm his observation from a large experience of Desert 
Sandstone country. Now, the Desert Sandstone, thus saturated with 
water, lies like a full sponge on the top of the outcrop of the Blythes- 
dale Bray stone, and must tend to equalise the supply by feeding the 
latter long after the rivers have ceased to run. 
The water-bearing beds of the Lower Cretaceous formation may 
not only be supplied from above by the Desert Sandstone, but I 
strongly suspect may be reinforced by the agency of strata geologi- 
cally on a lower horizon. Till lately the best information available 
led me to the belief that the Trias- Jura formation on Ipswich Coal 
Measures was succeeded conformably by the Lower Cretaceous or 
Bolling Downs formation, but in the last trip I have seen unmistak- 
able evidence of an unconformability between them. It may be that 
the bibulous lower members of the Cretaceous rest directly on sandy 
members of the Ipswich Coal Measures, which dip in the same direction 
in the manner shown in the following diagram : — 
e 
Shi 
cl Desert Sanc/sfone ( Upper Cretaceous.) 
b&b f Foiling Downs Formation [tower Cretaceous.) 
b States 
b 7 "BtythyesabteBra ystone 
C Dari /ng> Downs Bosa/t. 
d States, Sandstones & Coat Seams. 
e Toowoomba Basa/t 
[Trias dura. 
J 7 Murphys Creet Sandstone. 
Sha/eS; Sandstones & Cba/s of Tpsw/c/?.j 
| 8 Ba/aeozo/c Poets 
