THE GEOLOGY OF CENTRAL AUSTRALIA. 
89 
That raises the question “What is the Nullagine”? Wide areas in 
the Northern Territory and Western Australia have been assigned to 
the Nullagine, which series is usually found to consist of interbedded 
sandstones, conglomerates, slaty-shales, and limestones with intercala- 
tions of volcanic rock, trachyte, andesite, dacite, basalt, etc. 
David in “Explanatory Notes” stated that the Cambrian in 
Australia was remarkably free from volcanic action and igneous 
intrusions. That appeared to be true for the areas studied by him. If 
that statement is capable of general substantiation the limestone 
quartzite series carrying interbedded lavas in north-west Queensland, 
the Northern Territory, Central Australia and Western Australia must 
all be regarded as Nullagine. The more deep-seated intrusions which 
caused mineralisation in the series must also have been Nullagine. Thus 
the Wollogorang copper-field, the Maranboy tinfield, the Macarthur River 
silverlead deposits, and possibly the Hatch’s Creek wolfram field, and 
perhaps also the Tennants Creek gold-field and many other Territory 
fields could be regarded as Nullagine mineral deposits. 
Now there is no stratigraphical break between the so-called Nullagine 
and the Cambrian in most of the areas investigated by the writer. 
Wade in his long traverse of Northern Australia from the Kim- 
berleys to the Gulf of Carpentaria came to the conclusion that much 
of the so-called Nullagine was Lower Cambrian. He regarded the strong 
stratigraphical break between the highly folded metamorphic rocks and 
the gently rolling quartzite-limestone series as the base of the Lower 
Cambrian, whether fossils occurred in the rocks overlying the uncon- 
formity or not. Thus the Antrim basalts, which David placed in the 
Nullagine, according to Wade lie between the lower and Middle Cam- 
brian. The Edith River volcanics occupy practically the same horizon. 
The writer agrees absolutely with Wade’s viewpoint. The andesitic 
and rhyolitic volcanic rocks in the Wollogorang copper-field seem on all 
known stratigraphical evidence to occupy a horizon in the Lower Cam- 
brian. Tuffy horizons occur in the Cambrian Barkly Tabeland series 
between Anthony’s lagoon and Macarthur Station. The writer found 
a long wide diorite dyke penetrating a limestone-quartzite series near 
Macdonald Downs Station, north of the Plenty River ; the invaded rocks 
were regarded by Madigan as well as by the writer as Cambrian both 
on lithological and nearby fossil evidence. Moreover, rocks of an 
entirely Cambrian facies carry copper lodes on Yah- Yah Creek; some 
miles from Macarthur Station; the Wollogorang copper deposits, dis- 
seminated deposits, and the silver-lead and copper bearing reefs near 
the Nicholson River on the Border are in what appear typical Cambrian 
formations ; and Cambrian limestones contain abundant nodules of native 
copper near Delamere and Willaroo Stations in the Territory. 
