Canterbury and Westland. 363 



river, their deltaic deposits having considerably raised its bed. The 

 auriferous alluvium, forming a plateau washed by the sea, and reaching 

 to the western foot of the Southern A-lps, was afterwards to a con- 

 siderable extent preserved from destruction by the outrunning ridge 

 between the last-mentioned river and the Mikonui. The lithological 

 character of the boulders, of which this alluvium consists, gives us at 

 once an insight into the nature of the beds from which they are derived. 

 There are associated with them, dioritic sandstones, graywacke, con- 

 glomerate and breccia, clay, graywacke, and silicious slates, and 

 diabasic rocks all of which are found near the summits of the Southern 

 Alps, together with the fine-grained, light-coloured schists, character- 

 istic to that f Drmation. But a very considerable part of the alluvium 

 consists of metamorphic and plutonic rocks too numerous to mention, 

 but clearly indicating that the longest course of the river went through 

 rocks of that description, and that the greatest denudation has taken 

 place amongst them. It is evident, therefore, that the boulders, gravel, 

 and sand, of which those alluvial deposits are mostly composed, must 

 contain a great deal of gold, which, however, would not be worth 

 extracting, had not nature herself concentrated the precious metal in 

 numerous localities by sluicing the original accumulations on such a 

 gigantic scale as can only be effected by natural physical forces. This 

 "West Coast plateau, besides being intersected by a number of large 

 rivers, is nearly separated from the higher mountains forming the out- 

 running spurs of the Southern Alps by small streams running generally 

 in a northern or southern direction, before joining the main river. 

 The consequence is, that for a long period it has remained almost 

 intact, till smaller water-courses, derived from the surface drainage, 

 began to form channels, taking their source on the plateau itself, which 

 lias the character of a swampy plain covered with manuka scrub and 

 other vegetation peculiar to moist localities. I have already stated 

 that the older alluvium covers the highest young tertiary ranges, 

 which are of an altitude of about 800 feet, and repose unconformably 

 upon the cretaceo -tertiary strata near the Grey. Of these facts I met 

 numerous instances during my various journeys across these gold- 

 fields, where sharp razorback ridges have been formed, still bearing a 

 distinct capping of sub-angular boulders on their summit. It is thus 

 evident that when we meet with the original deep channels or leadg, 

 where during a long lapse of time the gold could concentrate, a rich 

 harvest may be expected by the gold miners. To such old channels of 

 concentration some of the goldfields of the Greenstone, Waimea, 

 Kanieri, Eoss, and the lately discovered Kumara diggings belong, 



