468 Tnnisdctious. 



or even in some cases nearly pure woody tissue, especially when the streams- 

 come from heavily bushed country. Again, as the land becomes more 

 submerged, any ridges which may exist mil be conve<L'ted into headlands 

 or capes, and in later stages even islands may be formed. Beach-pebbles 

 will occur, of course, but these do not necessarily occur at the margin of 

 the water ; indeed, in the case of a bay it is probable that the pebbles ^vill 

 1)6 deposited further out into the sea than in the case of open coast. 



Next suppose this area, once submerged, is gradually elevated. The 

 headlands and capes and islands will increase in size, the detrital deposits^ 

 will appear, and finally a flattish plain will make its appearance, extending 

 between the ridges and right up to the flanks of the range. The corrosive 

 action of the rivers will be lessened, and deposition will occur further up the 

 rivers, tending to increase the extent of the plain. 



Let us now apply these principles to the district we are concerned with. 

 Its physiography is exactly similar to that in the case we have supposed. 

 In the sea beyond the mouth of the Ourawera occur small islands, and there 

 are isolated peaks extending at intervals from Orepuki to Riverton. Be- 

 tween these is a succession of flat plains, with a gently rising slope from 

 the coast. At the locality of the claim there are the detrital deposits before 

 mentioned, and the whole range is densely bush-covered. We can therefore 

 suppose that at an earlier period in the earth's history the coast hereabouts 

 was depressed owing to continental oscillation or other causes ; that the 

 hollow or rounded surface of the bed-rock of the claim formed an old river- 

 bed down which a stream from the mountains carried at intervals silt and 

 vegetable growth, or both together ; that a bay formerly existed where now 

 the Ourawera discharges its waters into the sea, and that a long arm of 

 comparatively calm and shallow water extended from the bay up into the 

 river-valley. The stream then, on meeting the sea- water, would be com- 

 pelled to precipitate the material it brought down, and the deposits of the 

 claim would then be formed under the water. 



The flattish coastal plain would also be foimed about the same time. 

 Later on an elevation of the land took place. The Ourawera, bringing 

 down its debris, would have its grade lessened,* and consequently would 

 deposit the material higher up, and would enlarge the plain, besides covering- 

 its upper part with river-pebbles. The strata formed under the sea-water 

 would now appear close to the base of the range. Bush would grow over all 

 the plain, and the appearance it now presents would be formed. On this 

 theory, the elevation cannot at present be completed, or there was a former 

 much greater elevation of the land, which extencled further out than it does- 

 at the present day, for, as we have previously remarked, islands occur out 

 in the sea just beyond the mouth of the Ourawera, and these are distinctly 

 not volcanic. Further, the river must have been much larger than it now 

 is, otherwise it could not have deposited such large masses of lignite as do 

 actually occur — such as seams 5 ft. thick after compression. It is possible, 

 however, that it was assisted to some extent in this respect by wood washed 

 along the former shore and banked up in the quiet bay. 



It has been assumed that a submergence followed by an elevation 

 occurred, or, rather, as the river-bed shows, first a greater elevation than 

 now, then a submergence, f* llowcd by a smaller elevation than before, which 

 latter may still be going on. 



* With reference to the coastal district only; as before, the inner portion rcniaininif 

 steatly, or nearly so. 



