ANNIVERSARY ADDRESS. 59 
which overlie the kerosene shale at Doughboy Hollow, north of 
Murrurundi. It is doubtful, however, whether they are contem- 
poraneous with the Permo-Carboniferous Coal-measures. 
(B) Post-Triassic. With the exception of an eruptive boss of 
trachytic syenite near Mittagong, which is outside of the Blue 
Mountains proper, all the Post-Triassic eruptives belong to the 
basic group. Mounts Wilson, Tomah, King George, and Hay 
are capped with outliers of basaltic lava, as shewn on the geological 
map of the Rev. W. B. Clarke, at the beginning of his work on 
the “Sedimentary Formations of N.S. Wales.” As yet, as far 
as I am aware, scarcely anything is known about these outliers, 
and it would be a very useful work to map in their boundaries 
and describe them. At the Australian Kerosene Company’s 
Mine below Hartley platform a basic rock has intruded, and has 
considerably altered, in places, the kerosene shale, becoming 
bleached almost white in the process. Further east and situated 
close to the upper fold of the monocline are two very remarkable 
masses of volcanic breccia. The smaller mass is situated at 
Euroka Farm about five miles south of Penrith, and about half a 
mile west of the left bank of the Nepean River. (See Plate 1 — 3.) 
It is nearly circular in shape, about one-quarter mile in diameter 
and forms a depressed area, being completely surrounded by 
Hawkesbury Sandstone. The latter has been slightly altered 
along the contact zone. Evidence of the intrusive nature of this 
volcanic breccia is afforded by the fact that on the north margin 
a seam of coal, discovered in 1885, was found when followed down 
in a shaft to be almost, vertically inclined in the manner shewn 
on diagram 2 of Plate 3, and to end abruptly at about seven feet 
below the surface. It was possibly a large disrupted fragment 
floated up by the volcanic rock from the coal-measures about 
1,400 feet below, or perhaps derived from a thin seam of coal in 
the Hawkesbury Sandstone. The coal shewed very little sign of 
having been altered. The volcanic breccia is a tough black rock, 
the base of which is very opaque even in thin slices, and containing 
