SEDIMENTARY ROCKS OF THE LOWER SHOALHAVEN RIVER. 319 
(5) A very interesting example of extreme folding on 
Yalwal Creek. 
(6) The relations of the various subdivisions of the Upper 
Marine strata, with a glimpse at the local geography in old 
Paleeozoic times. 
(7) The nature of the habitat of many of the Permo- 
Carboniferous molluscs. 
For reasons dealt with later, the following division of the 
sedimentary rocks has been adopted :— 
DEVONIAN—Quartzites and Rhyolites. 
PERMO-CARBONIFEROUS—U pper Marine Series. 
(1) Conjola Beds 
(a) Freshwater beds with Glossopteris | contempor- 
(b) Conglomerates { aneous. 
(2) Wandrawandian Series 
(a) Mudstones at Burrier 
_(b) Sandstones of Grassy Gully » contemporaneous 
(c) Grits with Edmondia | 
(3) Nowra Grits 
RECENT—River Gravels and Alluvium. 
Devonian—tThis is the age consigned by Mr. Dun to the 
fossils collected from the large series of quartzites and 
other rocks, underlying the Permo-Carboniferous. They 
first make their appearance at Grassy Gully, where they 
consist of hard silicious rhyolites, showing beautiful flow 
structure. These have been described by Mr. H.C. Andrews.' 
Further west they outcrop at intervals, all along the river 
banks, as far as it was explored, that is nearly to the junc- 
tion of the Kangaroo River. In the neighbourhood of 
Yalwal Creek beautiful sections of unconformity occur, the 
folded Devonian standing out in marked relief to the Upper 
Marine sandstone above. 
1 Report on Yalwal Goldfield. p. 22. Geol. Surv. N.S. Wales, Mineral 
Resources, No. 9. 
