1864.] HECTOR OTAGO. 



127 



tion where it is breached by the sea. Over these clays come cal- 

 careous sandstone (b), containing abundance of fossils. 



Where Dunedin is situated volcanic energy was displayed at a 

 very early Tertiary date ; but nearly all our basaltic rocks overlie 

 the above-mentioned fossiliferous limestones, and were deposited to 

 what is now a height of (say) 1800 feet as submarine lavas and 

 tufaceous beds. The period of this volcanic energy was one of up- 

 heaval ; and since it closed I see no evidence of there having been 

 any great and general submergence of the island. On the other 

 hand, there must have been an excessive elevation, far exceeding, 

 at least in the mountain-region, that which it has at present. This 

 is proved by the great depth of the valleys, which were exca- 

 vated by glacier-action after the close of the above-mentioned forma- 

 tions. On the western coast the valleys have been scooped out to 

 a depth which is now at least 1800 feet, in some cases, beneath 

 the present sea-level, while on the east side, where the depression 

 has not been so great, these valleys are occupied by lakes, the sur- 

 faces of which have a mean altitude of 1000 feet, but the bottoms 

 of which are considerably below the sea-level. The evidence of the 

 former extension of the glaciers, arising from the greater altitude 

 and consequent enlargement of the area within the mean snow-line, 

 is most distinctly marked. On the other hand, except in one part 

 of the plains of Southland, I have seen no evidence of erratic de- 

 posits which have at all the character of the northern glacial drifts. 

 Distinct evidence of the Post-tertiary oscillation of the coast-line, 

 residting in emergence, is only to be found in the eastern, southern, 

 and north-western parts of the province. On the west coast, where 

 the mountains rise directly from the sea, and are penetrated by the 

 fiords, the evidence derived from the disposition of the detritus brought 

 down by the mountain-torrents, and thrown into deep water, indi- 

 cates rather a gradual submergence. Gabriel's Gully owed its rich- 

 ness to the gold having been freed from an ancient Tertiary drift- 

 deposit, that occupied a valley cut through obhquely by the present 

 watercourse. 



The strike of our auriferous schists is on the whole N.N.W., but, 

 so far as I have seen, they do not reach the west coast of this pro- 

 vince. However, gold has been recently found on the sea-shore of the 

 west coast of Canterbury, and within the last month a very promising 

 gold-field has been found in the northern extremity of this island 

 in the province of Marlborough. As the western part of the province 

 of Nelson, according to Dr. Haast, is partly composed of crystalline 

 rocks, it is very probable that the strike sweeps round to the N.E. 

 The western districts of the island being very inaccessible, this will 

 explain why the gold-diggings have been so long confined to Otago,and 

 to a small extent to Nelson, and would lead us to expect that they 

 may yet extend in a continuous belt right through the length of the 

 island, but passing to the west of Mount Cook. Nevertheless, I am 

 strongly of opinion that the richness of a gold-field is more de- 

 pendent on the extent of the auriferous drifts, and the relation of 

 the lowest level of the basins in which they have been collected to 



