58 PROCEEDINGS OF THE ROYAL SOCIETY OF QUEENSLAND. 
This table is necessarily generalised to some extent, and some of 
the correlations are only tentative. The absence of the fossiliferous 
sedimentary beds from the goldfields area makes it impossible to assign 
definite ages to pre-Pleistocene events. It no doubt took part in the 
general extreme uplift towards the close of the Pliocene (in Huon 
Peninsula, north of Lae, Pliocene fossils have been collected 10,000 feet 
above sea level) and it was probably about this time that the late porphyry 
intrusions and the associated volcanic activity commenced. It has been 
seen that vulcanism continued well into the Pleistocene, and it must, 
in all, have extended over a long period. Conglomerates of the Otibanda 
series contain gold derived from the mineralisation associated with it, 
so that sufficient interval must have elapsed for the cover under which 
this mineralisation took place to have been removed by erosion some time 
before the completion of the deposition of the lacustrine b’eds. These 
lake beds naturally also contain gold from earler periods of deposition 
and subsequent reconcentration from the conglomerates has contributed 
materially towards the gold in the recent alluvials. Even before volcanic 
activity commenced, the present physiographic system had been well 
established, the volcanics and the subsequent lake beds of the Otibanda 
series merely filling the deeper portions of the valleys, though the 
volcanics are also found much higher up the flanks of the mountains. 
Before their deposition commenced, the topography must have been even 
more rugged than it is at present. 
There seems little doubt that the Pleistocene lake outlet was through 
the wide, comparatively low Zenag Gap into what is now the Wampit 
River. This gap was closed by differential elevation during the drainage 
of the lake and the present stream system of the Lower Watut River 
established. 
REFERENCE. 
(1) Anderson, C. : Palaeontological Notes No. IV, Records of the Australian 
Museum, Vol. XX, No. 2, 1937. 
