Vll 
prefatory f{ote by tl]e Governn]eijt Geologist. 
This memoir is an important addition to the already lengthy list of contribu- 
tions, by Mr. Robert Etheridge, Junior, to the Paheontology of Australia. 
The Cretaceous rocks of this part of the world have hitherto been 
separated into two divisions, viz. : — 
Upper Cretaceous — Desert Sandstone Series. 
Lower Cretaceous — Rollnuj Duions Formation of Queensland. 
Our information in regard to these rocks is somewhat limited, no 
detail surveys of them having yet been made in the State of New South 
JUales. It seems advisable, however, to preface Mr. Etheridge’s Pala3onto- 
logical work wdth some brief notes on the geological characters and mode of 
occurrence of the rocks referred to, and it may lie stated at the outset that the 
Chalk formatiou, which, is such a remarkable feature of European Cretaceous 
deposits, is, so far as at present knowui, absent in Australia. 
The Rolling Downs Eormation was so named on account of the 
physiograjihical features of the large area of Queensland covered by it. 
This area, which forms good pastoral country, consists of vast plains or downs, 
the surface of which is composed of gentle undulations. The series consists 
of sandstones, shales, concretionary limestones, calcareous sandstones, marls, 
and gyjiseous clays. Tliese rocks are mostly of marine origin, but, according 
to Dr. R. L. Jack, freshwater beds containing plant remains and thin seams 
of coal also occur in them. General interest w’as attracted to tlie Lower 
Cretaceous rocks some years ago on account of the belief that they were the 
source of the artesian water supjdy. The basal beds of the series consist of 
very porous sandstones, wdiich w^ere first examined by Dr. Jack (late Govern- 
ment Geologist of Queensland) in the neighbourhood of Rlythesdale, near 
Roma ; Dr. Jack named these beds the Rlythesdale Braystones, and he is 
responsible for the statement that they form the actual intake beds of the 
artesian basin. ^ 
* Kept. Austr. Assoc. Ady, Science, 1S95, Brisbane Meeting, VI, p. 332. 
