58i 
fifty feet above the Severn Eiver. At the time such a coarse gravel was formed it is 
scarcely conceivable that the present Severn Valley existed, and its erosion was, there- 
fore, probably subsequent. Here, however, a question of great difficulty arises. The 
statement already made, that most of the present river channels ha ve been deepened by 
from three to six hundred feet since the last lava-flows, is generally correct ; but what 
appears to be a remarkable exception to the general rule occurs at Strathbogie. For 
about a mile above the head station basalt occurs in position a few feet only above the 
level of the present river; and, on the left bank of the same river, a shaft sunk through 
the lava proves that it extends to a considerable depth below the river channel. Also on 
Swamp Oak Creek, one mile north of the north-east corner of Portion .5, Parish of Astley, 
the basalt comes down within a few feet of the level of the creek. In the latter 
instance the position of the basalt may be partly due to landslips ; but the first case is 
incapable of such an explanation, and the interpretation of this phenomenon must 
be deferred until a geological examination is made of the country south of the Severn 
Eiver. 
“ These patches of Pliocene river gravel show that at the close of the Tertiary 
Volcanic period the outpouring of the lava streams by filling up the valleys had locally 
raised the level of the drainage channels. Eunning water, however, ceaselessly fretting 
the rocks, by degrees wore fresh troughs as deep as the old ones, and eventually 
considerably deeper. The heavy rainfall of the Pleistocene period must have materially 
accelerated this work of erosion ; but in this rocky district, with its steep falls, little 
trace is preserved of Pleistocene Deposits, except in the wide plains of coarse gravel in 
the valley of the Dumaresq. The shallow deposits of subangular gravel and sand in the 
beds of the present creeks and rivers wore evidently formed under conditions similar to 
those which now obtain ; and their stratigraphical position, as well as the occurrence in 
them of natives’ stone hatchets, proves them to belong to the recent period. 
Prom Dalton, near Gunning, there have been obtained the remains of a copious 
Tertiary land fauna, which Baron von Ettingshausen regards as of Eocene date.* Of 
this deposit, so far as we know, we have no representative in Queensland. 
In South Australia, as will be seen in the Chapter on the Desert Sandstone, that 
Formation is sometimes not separable from the Lower Tertiary. It appears as if the 
emergence of the land wliich took place in Queensland at or near the close of Mesozoic 
time did not take place in South Australia till somewhat later. 
We certainly have in Queensland an Older and a Newer Volcanic series, both 
chiefly basaltic, which may be presumed to be of Tertiary age, although direct evidence 
of their age is not forthcoming. The absence of evidence on this point may be due to 
some extent to the fact that the drift deposits beneath the basalts of Queensland have 
not been explored for gold as they have been in Victoria. 
Our Older Volcanic Series forms extensive beds, which cover the Desert Sand- 
stone, where the latter is present, or the still older rocks where it is absent. The Newer 
Series occurs as lava-flows or couUes, which have flowed down the valleys denuded out 
of the Desert Sandstone or out of the lower basalts. 
OLDER VOLCANIC SERIES. 
The granitic range dividing the Burdekin and Flinders waters is crossed by the 
road from Townsville to Hughenden at an elevation of 3,040 feet above the sea-level. 
The range is flanked on the eastern side by deposits of basaltic lavas extending to 
• Contributions to the Tertiary Flora of Australia, by Dr. Constantin, Baron von Ettingshausen. 
Mem, Geol. Survei/ JN'. iS, Wales^ Pal. i., 1888, p. 9. 
