370 



their channels ranch below the surface of the country, leaving the richest leads 

 in positions very inaccessible to the water supply required for raining, without 

 adopting a thoroughly organized system of irrigation, so that notwithstanding 

 the reputation of the West Coast as having almost the largest rainfall in tem- 

 perate regions, the gold fields there are actually languishing for want of the 

 supply of water so essential for gold washing. 



Otago, or Southern Gold Fields. 



The most extensive alluvial diggings in New Zealand are in this district, 

 and they possess peculiarities that distinguish them from most other gold fields. 

 Notwithstanding the large quantities of alluvial gold that has been obtained in 

 Otago, amounting to 2,548,999 oz., the actual aiming operations for the extrac- 

 tion of gold from the matrix, have, up to the present time, been comparatively 

 insignificant. 



The gold fields may be divided into two districts. In the eastern district 

 of the province the surface is undulating, and without being mountainous, has 

 a general elevation ranging from 1000 to 4000 feet. The prevailing rock in 

 this district is a very soft mica and chlorite schist cut by vertical joints, and 

 traversed by horizontal lamina? of qiiartz. The undulations of the surface, as 

 a rule, lie in a direction parallel with the east coast, and each ridge appears to 

 consist of a mass of the schist formation that has been tilted along its western 

 boundary, after the deposit of the Brown coal series (Miocene). A succession 

 of trough-shaped valleys are thus passed over in travelling from the east coast 

 into the interior, along the western side of each of which the Brown coal is 

 generally found to dip under very heavy deposits of alluvial gravels. 



The leading features of a section through this part of the province are 

 roughly shown in the accompanying diagram. ABC D.are the successive valleys, 

 with the intervening ridges, the most easterly of which shows the Brown coal 



formation, capped with Dolerite d, as at Saddle hill, and the others represent 

 Maungatua, Roughridge, and the Dunstan ranges, respectively ; a Schistose 

 rocks ; b Brown coal formation ; c Auriferous alluvium. 



Besides the quartz in a laminated form, veins of auriferous quartz exist, 

 and, as a rule, are situated along the lines that mark the lines of uplift of the 

 ranges, or in the positions marked by 1 2 and 3 in the above section, and 

 therefore on the west side of each of the ranges. These are not however to 

 be considered as quartz veins, in the sense in which the term is commonly used 

 in Victoria, and cannot be looked on as the only source from which most of 

 the gold in the Otago drifts has been derived. 



One of these reefs has been mined at Waipori and yielded an average of 

 one ounce per ton. Other reefs have been recently opened in the western slope 

 of the Dunstan ranges (3 in section), the results already obtained from which 

 promise much higher returns. 



No granite or Diorite dykes are known to exist in this eastern district. 



In the western, or Wakatipu Lake district, we find a much greater variety 

 of rock formation. The mountains are lofty and abrupt, and are cut in to sharp 



