10 
Coal Measures, and so, again, does the outcrop of the Muree Beds ; in fact. I believe that the 
outcrop of the Muree Beds to the east of Cessnock forms a greater re-entrant angle than is shown 
on the maps. It looks as though the axis of folding had originally been north and south, and 
that subsequent movements from southerly directions had buckled and perhaps sheered the 
Dome in this central portion. I am inclined to believe that the northern section of the Dome 
is approximately in its original position as formed, and that instead of being thrown down by the 
Greta Fault, it has rather resisted the elevation, which has gone on to the south of the Greta Fault 
around the old volcanic mass of Blair Duguid and that the direction of force causing this elevation 
has not been quite vertical, but slightly inclined from the vertical to the north-west. This, of course, 
would entail a certain amount of sheering, and. in my opinion, would explain the peculiar structural 
features present, which are difficult to account for in other ways, especially in the field. Some 
geologist has said that much light may be thrown upon large earth structures by the close studv 
of small things. For example, the pebbles in the conglomerates to be found in the beds which 
outcrop about the zone where the sheering forces would be greatest are frequently not onlv 
crushed, but distinctly sheerer! ; in fact, more examples of sheering than of crushing were noted, 
and some very fine specimens were collected bv us. This is not conclusive evidence, but it does 
throw light upon the nature of the stresses to which the beds have been subjected. 
The centre of uplift is the Blair Duguid volcanic mass. Mr. Millard ran his structural 
contours on the persistent sandstone horizon in the Lower Marine Series called the Ravensfield 
Sandstone, and found that they ran in concentric lines around that mass. The contours do not 
close, but are truncated to the north by the Greta Fault. For complete closure, therefore, he 
must assume that the Greta Fault has formed a barrier which is impervious to oil and gas, and 
that this rather considerable fracture has not allowed any petroleum to escape which mav have 
been present in past ages. This does sometimes happen, but not always, so the closure cannot 
be considered to be absolutely safe. Mr. Millard also estimates the amplitude of closure to be 
900 feet, which shows very sharp folding, and that the zone of closure embraces from 6.000 to 
10,000 acres of possible oil country.* 
The Belford Dome is open to no objection, so far as 1 was able to discover, from a structural 
point of view. It is developed in the Branxton Beds and the Muree Hock of the Upper Marine 
Series. The Muree Beds outcrop in a complete oval orientated north and south : the long or 
north and south axis being 10 miles in length and the east and west axis 5 miles. The village of 
Belford lies almost exactly at the centre of the Dome. The conglomerates of the Muree Beds 
can be traced almost completely around the Dome, and dip off from the centre at low angles 
varying from 4 degrees on the east flank to 9 degrees on the west. It was formerly thought that 
the Lower or Greta Coal Measures lay at too great a depth below the surface in this area to be 
profitably worked, and Professor David's sections show the Muree Beds to be below the surface. 
The fact that these beds outcrop at the surface also connotes that the Greta Coal Measures come 
much nearer to the surface than was supposed, so near, in fact, that they can be reached in this 
area at a depth which would not make working unprofitable. This alone justifies the work which 
Mi-. Millard has done, and may prove very profitable to the State of New South Wales in due course. 
The fact that the Greta coals come much closer to the surface in this locality has been confirmed 
by a boring put down at the point indicated on the map. This penetrated to a depth of about 
1.460 feet and passed through 5 feet of coal at this depth. Some bursts of gas were met with 
during drilling operations, but 1 was unable to obtain particulars as to the nature of the gas. 
5. Evidences of Petroleum in the Sydney Basin. 
No positive evidence of any importance of the existence of petroleum in the beds forming- 
the Sydney Basin has yet been discovered. Small showings of oil on the surface of the water 
and in the muds of Nepean River have been referred to. but Mr. Carne and the officers of the 
Geological Survey point out that the spot where such showings have been noted is not far from 
" a long-used boat landing,' t and that motor launches and oil tins are constantly in use near this 
spot. Judging by the outcry which has arisen concerning the contamination of foreshores, 
harbours, and fishing grounds, owing to the use of crude oil by different kinds of boats, there 
is much force in this objection. Oil may pers.st for a long time on the surface of water, though 
it is readily carried down to the bottom by settling particles of mud, so that occurrences in such 
circumstances must be regarded with great suspicion. 1 have also heard of similar showings 
on the Hawkesbm v River, in addition to the above objections there is an additional one in this 
ease. While inspecting the Kerosene Shale Works at Newnes. Mr. John Fell drew my attention 
to a large drainage tank near the banks of the Wolgan River. Into this tank waste oil from the 
whole of the plant and workings is drained and saved when the plant is running. At the time of 
* Loc. pit. p. DU. 
v tan. , 1 . Jnjifs. — Lot. fit. p. 30. 
