Middle Devonian Roche. 
4o 
All these patches and outliers are similar in lithological cha- 
racter to the typical limestones of Buchan, and contain the 
characteristic Middle Devonian spirifers found in the latter. 
The above-described marine limestones, whose total thickness 
is estimated at 400 or .500 feet only, form the upper portion of 
the Middle Devonian group, which they serve to identify. The 
hase of the group is composed of rocks of a different character, 
which are found underlying the limestones and intervening between 
them and the (Lower Devonian) Snowy River porphyries. 
This subject has been ably worked out by Mr. A. W. Howitt, 
from whose notes on the Devonian rocks of North Gippsland, 
published in the Geological Progress Report, No. V., pages 117 
and following, I extract the following leading observations : — 
The lower beds of the Buchan group exhibit a thickness of 
from 700 to 1,000 feet of calcareous tufas, felsite tufas, breccias, 
&c., between which and the Snowy River porphyries certain 
well-marked distinctions are noticeable. As previously shown in 
describing the latter, no traces of aqueous action in their arrange- 
ment can be observed, and the volcanic materials which compose 
them appear to have fallen, and to have been arranged, on land ; 
whereas, from the base of the Buchan series and upwards to the 
unmistakably marine limestones, the tufas, breccias, &c., are of a 
character which clearly indicates that their component volcanic 
. and other materials fell into, and were arranged by, water. From 
the parte ul are given by Mr. Howitt in a number of sections, the 
lowest beds consist of unstratified breccia-conglomerates, composed 
of rounded and angular felsite blocks, with fragments of slates and 
sandstones resembling those of the Lower Palaeozoic formations. 
Above these occur fine and coarse breccia-conglomerates made 
up of similar fragments and sandstones composed of felsitic grains, 
all showing to a greater or less extent- distinct signs of bedding. 
A sheet of compact felsite and one of basalt, apparently repre- 
senting lava-flows, are shown as occurring above these in one 
section given by Mr. Howitt. 
On thick red beds, resembling sandstones, rest the lowest lime- 
stones, above which occur thick yellow beds, apparently cither de- 
composed felsites or consolidated felsitic mud. These are followed 
by thin-bedded limestones, some of which contain numerous 
angular felsite fragments, deposited either irregularly or in bands; 
above those lie the thicker bedded compacf blue limestones. The 
following are verbatim quotations from Mr. HowitPs treatise : — 
“ The°Buchan limestones are therefore only part of a continuous 
series. The lower part of the group consists of coarsely aggregated 
felsitic breccias, the coarseness of material decreasing, but with 
alternations of texture, in ascending. The deposits also become 
more distinctly bedded, and in places, as at Butcher’s Creek, pass 
into or alternate with subordinate conglomerates in which angular 
or rounded fragments of sedimentary rocks are of common 
D 
