VOLCANIC ACTIVITY IN SOUTHERN QUEENSLAND. 109 
Permo-Carboniferous Volcanic Activity 
in Southern Queensland. 
By Proressor H. C. Ricuarps, D.Se., and W. H. Bryan, 
M.Sc., University of Queensland. 
(Plate IV., and Text-figure 1.) 
(Read before the Royal Society of Queensland, 24th 
September, 1923.) 
(I.) Introduction. 
(II.) The Silverwood-Lucky Valley Area. 
(III.) Petrology. 
(1V.) Comparison with other Permo-Carboniferous 
Voleanics of Australia. 
(V.) Earth Movements and Igneous Activity. 
(I.) INTRODUCTION. 
During the course of field investigations carried out in 
recent vears in the Silverwood-Lucky Valley area, some 10 
miles to the south of Warwick, the authors were particularly 
impressed by the fine development of great series of lavas 
and tuffs met with in several parts of the district. Both 
the flows and the associated pyroclastic rocks are for the 
most part of an acid nature, but more basic volcanics are 
represented in the upper part of the series. On account of 
their effective resistance to weathering, the rocks under 
discussion are generally the dominating topographical forms 
in their immediate locality, and in some cases cause 
important divides. 
The thickness of this great series of volcanics as 
exposed in the Eight Mile Fault Block is about 5,000 feet, 
but there is reason to believe that a large strike fault has 
caused duplication, so that a minimum thickness is in the 
neighbourhood of 2.500 feet. However, since the uppermost 
beds in this faulted area may not represent the last phases 
of vuleanicity, and as the voleanic material found in the 
