122 PROCEEDINGS OF THE ROYAL SOCIETY OF QUEENSLAND. 
zlomerates are developed, but these are very low down in 
the series. Dunstan regards them as belonging to the Lower 
Marine division of the Permo-Carboniferous, while Jensen 
believes them to be even older. In addition to these there 
is evidence of voleanic activity in this area in the shape of 
basaits interbedded with the Upper Marine strata. The age 
of these corresponds with that of the volcanics under 
discussion, but very little petrological evidence is available 
for purposes of comparison, 
(f) The Mackenzie River Area.—In the Mackenzie 
River area, also, basalts interbedded with Upper Marine 
strata are known. Andesites, the horizon of which has not 
been definitely established, are found both in this and in the 
Dawson River areas. 
(V.) EARTH MOVEMENTS AND IGNEOUS 
ACTIVITY. 
The history of the Silverwood area may be briefly 
summarised as follows:—In Middle Devonian times exten- 
sive submarine outbursts resulted in the accumulation of a 
great thickness of andesitic tuffaceous material. This was 
immediately followed by the deposition of material which 
ultimately became a series of banded radiolarian cherts and 
mudstones. Pronounced orogenic movements in Late 
Devonian times (the Kanimbla Epoch of Stissmilch) 
compressed this ‘‘Silverwood Series’’ into isoclinal folds 
and elevated the Silverwood district into a land area, which 
it remained throughout the Carboniferous Period. During 
the latter part of this period very considerable igneous 
activity was in progress further to the south, in the New 
England district, but if the Silverwood area was also the 
scene of such activity there is no evidence of it. At the 
close of the Carboniferous period, and doubtless as the 
result of what in the New England area Siissmileh and 
David have described as the ‘‘Hunterian disturbance,’’?° 
the Silverwood area was depressed below sea-level, and 
fossiliferous strata equivalent to the Lower Marine of the 
Hunter River district were deposited. These seem normal 
sediments, for the most part laid down under shallow water. 
and show no signs of violent contemporaneous volcanic 
activity such as that which accompanied the accumulation 
of sediments of this age in the Drake area some 50 miles to 
10 Proc. Roy. Soc. N.S.W., 1919, p. 282. 
