Kak(JU1Iarson. — The Plati/inm Gravels of Orejmki. 463 



more gentle, and the stream meanders in broad curves through alluvial 

 lands of its own manufacture. 



With the three streams above we have the mountain tract projiounced, 

 followed by a more or less pronoimced valley tract. The plains tract is 

 very evident, being shown by the complicated meanders of their courses. 

 A similar course is followed by some rivers in the North Island, especially 

 the Wanganui. This river, coming from the plateau of the centre of the 

 mainland, flows in its lower portion through flat plains which quite recently 

 (in the Pliocene) were beneath the sea-level. Complicated meanders are 

 thus produced, and in this case, as in others, lakes are in process of formiiig 

 by the erosive action of the waters on the banks. This action is especially 

 to be seen in the case of the Orawia and Waimeamea. 



It is usually miderstood that rivers acquire complicated meanders hi 

 their courses comparatively late in their period of existence. The work 

 which a river unceasingly carries on is the bringing of its bed to its base- 

 level of corrosion, after which the slow erosion of its banks begins. But, 

 while this is true in most cases, it is not always true. As Professor Russell 

 points out, a similar phenomenon may be witnessed with even young rivers, 

 when the land through which they flow has recently been raised from 

 beneath the sea, and, as will be showm afterwards, it is probable that such 

 has been the fate of at least some of the coastal part of the district. 



Finally, the Waiau River has to be considered. Easily the largest of 

 the Southland rivers, this notable river has a discharge of about 1,130,000 

 cubic feet of water per minute, or two-thirds the amount of the Clutha 

 River. Though broad and deep, it is, even when flowing across theplainf^, 

 unfortunately too rapid for navigation. Unlike most rivers, it starts away 

 as a large river from, not a hillside, but from the southern extremity of 

 Lake Te Anau, the largest lake of the South Island of New Zealand. After 

 rushing swiftly over eight or nine miles of large boulders between high 

 banks it enters Manapouri Lake. From this it emerges at the south-east 

 corner, to be joined alm.ost at once by the Mararoa, itself a good-sized river. 

 Some fifteen miles further on it receives the water from the Monowai Lake 

 and the Hunter Mountains, and thenceforth, with a rather tortuous course, 

 it flows in a southerly direction to empty its waters by several mouths into 

 Te Waew^ae Bay. 



In addition to these features, a lake occurs in the district midway 

 between Wakapatu and Colac Bay. Lake George, as it is called, is only 

 about 100 chains long and 60 broad. The depth is in no case more than 

 15 ft., and this fact, together with the marshy nature of the surrounding 

 land, gives the impression that it is either a relic of a former depression or 

 is due to depression actually in process. It is supplied by a small unnamed 

 spring from the lowest spurs of the range. 



Of the beaches which occur along the coast all that need be said is that 

 they are imusually flat. At Orepuki the beach at low tide extends for 

 fully 50 yards along the sand to the margin of the water. 



Geology of the Claim. 



It has already been remarked that the whole district extending for 

 about two miles from Oiepuki Township into the Longwood and along the 

 base of the range about Romid Hill to the edge of the coastal plain 

 consists of a mass of diorite, possibly as an intrusion. This rock forms 

 the base or bed-rock of the claim, and therefore calls for close attention. 



