VOLCANIC ACTIVITY IN SOUTHERN QUEENSLAND. 119 
interest. However, it may be instructive to compare the 
Silverwood-Lucky Valley flows and tuffs with various other 
occurrences which have some features in common with them. 
It will be noted that where petrological comparisons reveal 
similarities, a consideration of the respective ages shows a 
lack of harmony, and on the other hand where the ages are 
in agreement the petrologieal characters are essentially 
different. 
(b) The Southern Coalfield of New South Wales.— 
Harper has described a series of lavas and tuffs about 1,000 
feet thiek from the Cambewarra-Kiama districts, the age of 
which agrees closely with the Silverwood-Lucky Valley 
Series. ‘‘These consist of seven submarime’’ an 
(followed by) . . . . ‘“‘two terrestrial lava flows, 
intercalated with beds of Permo-Carboniferous age consist- 
ing mainly of voleanie tutfs.’’* Of these flows the ‘* Blow- 
hole Flow’’ ‘‘was apparently the first manifestation of 
voleanie aetivity in the shape of lava flows during the 
Upper Marine epoch, within the Southern Coalfield, and it 
is interbedded with tuffs containing marine fossils.’’* With 
regard to the uppermost ‘‘Minmurra Flow,’’ Harper states 
that ‘‘The horizon occupied is about 120 feet above the top 
of the Cambewarra flow or its equivalent boulder horizon,’’’ 
which marks the upward limit of marine fossils. The 
Berkley Flow is also interbedded with the freshwater 
sediments overlying the Upper Marine. 
This evidence forces on one the conclusion that the 
voleanies of the Southern Coalfield were practically con- 
temporaneous with those of the Silverwood-Lucky Valley 
area, but here all resemblance ends. Chemically the two 
groups are essentially different, and this difference is 
reflected in the petrography. Harper describes the 
voleanies of the Southern Coalfield as ‘‘a petrographical 
provinee of Permo-Carboniferous age possessing definite 
ehemical characters and notably a high potash content.’” 
In the series under discussion the alkalies are not high, and 
soda predominates. This marked difference can best be 
3 Harper, L. F.. Memoirs Geol. Sur. N.S.W., Geol. No. 7, p. 49. 
4 Harper, L. F., op. cit., p. 307. 
5 Harper, L. F., op. cit., p. 292. 
6 Harper, L. F., op. cit., p. 278: 
