Marshall. — The Glaciation of Aew Zealand. 345 



In regard to the topography, the statement was naade that the form of 

 the surface features has only lately been revealed, owing to the effect of the 

 advancement of settlement, and the consequent destruction of forest which 

 previously concealed it. This is certainly not true of the country between 

 Turangarere and Ruapehu, a distance of fifteen miles, which has always 

 been open grass land, and must have been crossed by any supposed glacier 

 which extended from Ruapehu to Utiku. Yet this country has been visited 

 by numerous geologists, all of whom have failed to record any indication 

 of glacial topography. The last of these, Mr. Speight, in an article on the 

 geology of the Tonga riro National Park, makes no mention of any glacial 

 features on Ruapehu or the surrounding country outside the area of the 

 present glaciers. The country between Ruapehu and Waiouru consists 

 near Waiouru of river - gravels covered with a thin deposit of volcanic 

 matter, and nearer to the mountain lava-flows take its place. Southwards 

 from Waiouru, hills for the most part flat-topped, and all formed of Caino- 

 zoic rocks of late Miocene or Pliocene age, extend to the limits of tli(^ 

 supposed glaciation. Near Waiouru the flat-topped hills have a stratum 

 of hard shell-limestone forming the summit. This dips south-eastward 10^, 

 and on its north-westward face there is a steep scarp such as is normally 

 formed in such country by stream-action. I have carefully examined the 

 surface of two of these scarps, and I can assert that they bear no signs what- 

 ever that they have been submitted to glacial action. The topographv of the 

 land near Taihape does not in any way differ from that of country of a similar 

 age and structure in the neighbourhood of river- valleys in many other districts. 



In many places in the Hautapu Valley and other river-valleys hillocks 

 of many different sizes and altitudes are covered with a deposit that is at 

 times well-stratified gravels with boulders of many sizes, and in other places 

 finer and more clay-like deposits, still with some boulders in them. These 

 are the " boulder-clays " of the paper referred to. 



Road-cuttings outside of the Hautapu Valley and other river-valleys 

 do not show these gravels or clays. The boulders in the deposits of the 

 Hautapu Valley consist, except for a few fragments of Cainozoic rock, 

 entirely of andesitic blocks, and doubtless come from Ruapehu. My 

 observations showed that the blocks are not markedly angular, and no 

 striated boulders have yet been found in the deposits. 



The occurrence of these gravels and boulders is easily accounted for. 

 The whole of this part of the land has been elevated between 2,000 ft. and 

 4,000 ft. within the latest Cainozoic times. During the movement of eleva- 

 tion the rivers have been filing their way downwards. When the upward 

 movement temporarily ceased or was relatively slight, the rivers widened 

 their beds, and deposited gravels or finer matter over their flood-plains. 

 Volcanic action being then in progress, eruptions provided fine and coarse 

 matter in a most irregular mixture, as at Martinique and St. Vincent. 

 When the upward movement again became more rapid they filed their beds 

 down ; and during another period of little movement the old flood-plain 

 was dissected until in some places no trace remains of it except a few iso- 

 lated hillocks. This perfectly normal action is in all countries known to 

 account for the occurrence of gravels and other river-doposits at manv 

 different levels in the same valley. It has been stated that the boulders 

 referred to are larger at Utiku than they are nearer to Ruapehu. My 

 observations certainly do irot agree with this. I saw larger boulders at 

 Turangarere than elsewhere: and accurate comparative measurements are 

 certainly necessary to establish the reverse statement. 



