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Rh they will peter out altogether, and certainly their gold-content will not justify sinking on the outerop. That they have had their indirect valuc, however, is undoubtedl, and they must have helped in some measure to supply the alluvial gold of the drifts.

Barren Reels, or Buek lees. These are peculiar types, and correspond to similar occurrences on the llauraki gold fields, in California, and in a great many other vein distriets. In Otago they consist of very wide, massive, bold outcrops of "bungry" glassy quartz, often traceable for considerable distances. They are practically barreu, devoid of pyrite, and composed of quartz throughout.

A typical buck reef occurs near the Hawksburn Homestead, six miles south of Bannockburn. Several occur at Quartz Reef Point, on the Clutha River, four miles above Cromwell. Another occurs at Nenthorn, and another m the Nokomai district. An interesting buck reef occurs near Waipori, on the road to the Waipori antimony-vein. Where it outcrops it consists of 2 ft. of quartz, auch of which is in very fine pseudomorphs after calcite, and preserves excellently the rhombobedral cleavage. It is, however, not proved that this is a buck reef, as no tests have been made of the quartz.

GENERAL OBSERVATIONS ON THE VEINS.

(1.) The Vein-fissures.

Mature of the Fissures. The fissures which carry the veins of Otago vary greatly in nature, according to the physical character of the particular zone of schist through which they pass. Where the schist is resistant and quartzose the fissures are simple, being narrow and defined, as at the Carrick and Bendigo: where the rock is softer the fissures are compound, ill-defined, and longer, and become shear-zones of some width, as at Skipper's and Macetown. Finally, at Jacrae's the shear-zoves follow the foliation-bedding planes, so that here we have a group of bedded or segregated veins. Thus the division of the veins into groups, first used by Ulrich, is made possible by the above fact-the varying nature of the schist and the consequent varying nature of the veins in different localities.

Professor lark speaks of the vein-type at Bendigo as a twin fissure containing a band of schist between.* I can see po evidence of this, and I regard such a vein as a single fissure filled by quartz, except where portions of country rock have been detached from the walls of the fissure by sub- ordinate eracks, giving the quartz vein a varying thickness. Orientation. The mean strike of the gold-bearing tissures is west and cast, or slightly to the north of west, although locally the strike varies through all points of the compass, as on the Carrick Range. Distribution. The local distribution of fissures as shown on the map is in part more apparent than real, for there is no doubt that the whole goldfield is traversed by veins, even in localities where they have not been located. This is due in part to the absence of prospecting in less inviting districts, and in part to the fact that veis might readily be overlooked in tussocky country where shoots or blocks of quartz did not happen to outerop. Nevertheless, there is evidence of a localisation of fissures into more or less defined groups. This is probably due to local factors, such as the nature or previous disturbance of the schist. which aided or retarded the fissuring- forces.


 * Park, Bull, No. 3. N.Z.G.S., 1908. 1. 43.