Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/437

1869.] ULRICH-"NUGGETTY REEF." 327 granite boundary. That the granite could scarcely have exerted any upheaving action upon the Silurian formation is well shown by the fact that both the strike and dip of the beds are against the granite, and show no material alteration in these particulars for miles away from the latter.

Close around the foot of Mount Tarrangower, within the north-eastern quadrangle, lies the thriving little mining town of Maldon, enclosing within its boundary some of the richest auriferous quartz-reefs of the district, and forming, as it were, the nucleus from which, towards the north, east, and south, auriferous Postpliocene gullies and chains of hilly patches of Upper Pliocene gold-drift diverge.

Both gullies and drift-hills (once highly auriferous) are now nearly worked out. Washing on a large scale might still perhaps prove a profitable undertaking, if a great scarcity of water did not put this beyond the power of the enterprising miner. The chief resource at present of the mining community of Maldon, and what has made this gold-field celebrated, are its numerous auriferous reefs; and amongst these the one named at the head of this article ("the Nuggetty reef") is no doubt the most remarkable, both on account of the great quantity of gold obtained from it, and because it exhibits some interesting geological features that throw a clear light upon its age relatively to that of the granite. The reef was discovered in 1856, receiving its name from the coarse, nuggetty gold found in its outcrop, and it has yielded up to the present time very little short of 300,000 ounces of gold; some portions are said to have paid from 300-500 ounces of gold per ton. It lies about two miles and a half N.N.W. of Maldon, appearing first on the surface several chains north of the top of the high east and west range that commences from near this point to form the watershed between the Muckleford and Bradford Creeks, and it terminates against the granite at the foot of the range, diminishing gradually and dividing into thin veins, which do not penetrate that rock. It strikes N. 12° W., and dips easterly at angles varying from 70° to nearly vertical. It cannot in reality be regarded as one well-defined lode, as it consists of separate veins, and shows irregularities and different aspects in different portions of its extent. At the north end, for instance, which is principally worked by the Alliance Company, it consists of two strong veins, divided by a somewhat irregularly shaped and bedded mass of bluish-grey hard, metamorphic sandstone — a so-called "horse," which is more or less abundantly traversed by quartz-strings. At the surface the two veins adjoin each other very closely, and have perhaps once been united in the original crown of the reef, since removed by denudation. Owing, however, to the "horse" gradually expanding to a certain point, then contracting and again increasing in width, the veins diverge, converge, and diverge accordingly.

The eastern vein is distinguished by a fine smooth eastern wall that extends without any change as far as the line of the reef has been opened and examined; the western vein, on the contrary, is devoid of a defined wall, and shows no casings, and the quartz presents