Vll 
STKATirilUrmCAL NOTE ON THE EISII-BEl) AT THE lUIIAVAY 
ITVLLAIST QUARBY, NEAR GOSEORD. 
Evidence for determining the geological horizon of the Eish-hed in the 
ahove qnarry is afforded hy the diamond drill l)ores at Ourimhah and Wyong 
to the north, and Mnllett Creek and the -Tarley Eoreholc to tlie south, as well 
as hy natural sections presented ])y the surrounding lulls of Ilawkeshury 
Sandstone. 
The natural sections between the outcrops of the Permo-Carhoniferous 
Coal Measures at Coal Cliff on the south, ami Lake Maccpiaric on tfio nortli, 
show that Cfosford is situated ])rohal)ly near tlic middle of the basin, as the 
strata here are nearly absolutely horizontal, whereas to the north of Gosford 
they have a general southerly dip, and at a short distance south of Gosford a 
northerly dip. At tlie Ourimhah Bore, six miles northerly from Gosford, 1,425 
feet of strata were pierced l)y the diamond drill ivithout the Coal Measures 
being reached. The greater }>art of the strata in this bore, ])ctwcen 450 and 
1,150 feet, consist of tine shales of a chocolate, rod, or green colour. Micro- 
scopic examination shows the green shales to he largely composed of tuffaccous 
material like the cu})riferous shales proved in the ITolt-Sutlierland Bore, and 
it is prohal)lo that miicii of the chocolate and red slialo is composed of altered 
tuffaceous material, intermixed A^•ith the sedimentary. At the AVyong Bore, 
ten miles northerly from the Ourimhah Bore, the Coal IMcasurcs were struck 
at a depth of 787^ feet, the first 400 feet (approximately) being probably in 
the same strata whicli were proved in the lower portion of the Ourim1)ah 
Bore. Allowing an increase of about G50 feet of strata between the Ourimhah 
Bore and Gosford on account of the dip, the .approximate thickness of strata 
intervening here between the Eish-hed and the Coal Measures would he 
about G50-[-l5425 387 — 2,4G2 feet (approximately). Tlie Mullet Creek 
Bore, about ten miles southerly from the Gosford Quarry, was carried to a 
depth of 1,338 feet without the Coal Measures being reached, the lower 
500 feet being chiefly in chocolate and green shales. The depth to the Coal 
