. HuTTON. — The Geological History of Neiv Zealand. 179 



Now, it seems likely that during this time the early winter 

 snows would kill many moas, as well as other birds, on the 

 hills, and that their bodies would be washed down on to the 

 lower grounds by the spring floods, so that in time immense 

 quantities might accumulate in the hollows. This specula- 

 tion is much strengthened by the fact that no large deposit of 

 moa-bones has ever been found in any of the swamps on the 

 plains away from the hills, either in Southland or in Canter- 

 bury, or in the Waikato and Piako districts. However, we 

 should also remember that some parts of these plains may 

 have been below the sea at that time, for we have evidence 

 that after the culmination of the glacier epoch a great depres- 

 sion of the land took place until it stood lower than it does now. 



Eaised beaches with recent species of marine shells have 

 been found at Tauranga at an elevation of 25 ft. above the 

 sea; at Taranaki, 150ft.; at Amuri Bluff, 500ft.; and at 

 Motunau, 150 ft. above sea-level. Also old marine terraces, 

 but without shells, exist on Mahia Peninsula at 200 ft. to 

 300 ft. of elevation, as well as near Wellington ; and all along 

 the w^est coast of the South Island as far as Green Islet, south 

 of Preservation Inlet. We may therefore safely infer that 

 the South Island and the southern part of the North Island 

 sank in the Pleistocene to a considerably lower level than they 

 now attain, and that tliey are once more rising. 



The evidence given by the alluvial deposits of our rivers is 

 also quite in accord with that of the sea-terraces. When the 

 land was sinking the rivers filled up their valleys and formed 

 the broad alluvial plains so common from Southland to the 

 Waikato. When the land began to rise again the remarkable 

 series of river-terraces which catch the eye in most of our 

 valleys were formed out of these alluvial deposits. 



The origin of the silt deposit — sometimes called loess — 

 which is found on the eastern side of the South Island is a 

 difficult problem to solve. It is found chiefly from Invercar- 

 gill to the Mataura River, and from Oamaru to Timaru and 

 Banks Peninsula, lying on the low hills and on the river 

 gravels. It evidently forms the latest deposit in every 

 locality in which it is found, and it is equally evident that it 

 is not being formed now. Two theories have been advanced 

 to account for it. One is that it is a wind-formed deposit 

 analogous to the sand-dunes of a desert. The other is that it 

 is a marine deposit, but formed very rapidly by the floods of 

 our diluvial epoch washing away the fine mud left by the 

 retreat of the glaciers.* Many objections can be made to 

 both of these theories, but it would detain me too long to 

 discuss them. 



* Trans. N.Z. Inst., vol. xv., p. 411. 



