152 
Mariner’s Reef. 
The Mariner’s reef strikes N. io deg. W., and dips 85 deg. W., and 
occurs in the middle auriferous belt of the Ordovician slates and sand¬ 
stones. 
This belt shows the maximum amount of folding in the Maryborough 
beds, which have several synclinal and anticlinal folds adjacent to Mari¬ 
ner’s line, and the underground structure shows that Mariner’s reef cuts 
the strata close to a synclinal axis; the beds in the lower levels being 
75 deg. east and the reef 85 deg. west in dip. 
A nearly flat horizontal offshoot or lateral branch of dyke rock cuts 
the reef and strata, and is seen at intervals in the 523-ft. level. It has 
a very slight dip to the south-east, and is about 4 feet thick in places. 
This flat dyke has its origin from a main vertical dyke which I found 
in the end of trie 100-ft. western cross-cut at the bottom level. These 
dykes, where they intersect reefs, appear to have a very favorable bearing 
on the auriferous shoots occurring in the middle belt. The dyke rock has 
been sliced and examined by Mr. D. J. Mahony, M.Sc., F.G.S.,. who 
classes it as a minette of fairly fine grain, consisting of orthociase felspar, 
black mica, and some hornblende with secondary calcite and serpentine, 
which probably represents original olivine. Gold has been obtained above 
and below this flat dyke branch and was especially rich in the Little reef 
shoot. Should another flat dyke branch cross the reef below the bottom 
level, rich stone may again be found. If the main dyke and reef keep 
their present dip towards one another, they will meet at a little less than 
1,000 feet from the surface, and there is then a possibility of an enrich¬ 
ment in the reef, especially if another block makes on the Little reef 
channel below the 625-ft. level. An assay of the decomposed dyke 
(No. 632 assay) gave a trace of gold, which is interesting as the specimen 
was collected away from any quartz. 
The Reef .—The main reef has been worked for over 1.000 feet north 
and south, and was apparentlv a very large reef formation of low grade 
quality underlying a very rich smaller make known as the Little reef, 
which lies to the north partly on top of the big stone, but in the same 
teef channel. 
Report states that this Little reef has yielded as much as 60 oz. to 
the ton from No. 8 claim south, in a patch, and authentic records taken 
from the Maryborough Advertiser show yields from 3^ oz. up to 8 oz. 
to- the ton from stone 2 feet wide in places. 
This rich Little reef pitched north at 45 deg., or 1 in 1, and dipped 
85 deg. W., cutting beds dipping 75 deg. E. Its average width is 
reported as over 1 foot and up to 2 feet and 4 feet in places, and it con¬ 
sisted of laminated blue-white quartz, very heavy and carrying iron pyrites 
and galena. 
Workings .—The main shaft, which has just been repaired, was sunk 
to a depth of 632 feet to the bottom of the well. At 60 feet cross-cuts 
east and west have been put in, but are now filled up and inaccessible. 
In the western cross-cut the manager, Mr. Williams, informed me that 
he noted two reef makes and all the beds dipping to the east. 
At 346 feet a cross-cut was put out east for 158 feet, exposing reef 
tracks at 28 feet, 59 feet, and 138 feet. A slide or fault was passed 
through just in from the shaft, and hading 60 deg. E. The beds dip 
75 deg. W. right out to the end of the cross-cut, where an anticlinal 
fold changes the dip to the east. 
