334 Transactions. 



Art. XLIII. — The Gla^iation of New Zealand, 



By P. Marshall, D.Sc, Professor of Geology, Otago University, 



^Read before the Otago Institute, lAth September, 1909.] 



It is needless at this stage of the observation of the surface features of 

 New Zealand to insist on the fact that in the latest geological times all the 

 present glaciers were much extended, and that numerous glaciers existed 

 where there is now no ice. In regard to fundamentals, in recent years few 

 additions have been made to the amount of information that was possessed 

 by Hutton, Hector, and Haast in the early " seventies." 



There has, however, been a large amount of detailed information gained 

 in regard to several of the former glaciers in many parts of the country, 

 and in regard to the actual extent of many of those glaciers. All those 

 surface features due to glacial sculpture which have been recorded and de- 

 scribed in other glaciated countries have been recognised in New Zealand, 

 especially in the upland and western districts of Otago and Canterbury. 



Generally it may be stated that in the north-w^est of the Nelson Province 

 signs of glaciation have not been found at a lower level than 4,000 ft. above 

 sea-level, while in the eastern portion of this province, where the moun- 

 tains do not often exceed 5,000 ft. in height, there appears to have been 

 no important accumulation of ice whatever. Further south, the glaciers 

 that filled the basins of the present lakes Rotorua and Rotoiti had their 

 terminal faces at an altitude less than 2,000 ft. above sea-level. This 

 relatively small altitude is easily explained by the situation of the lakes, 

 for thev lie between mountain-ranges, and in country that is continuously 

 high, which afforded a large gathering-ground for snow and ice. 



The effects of glaciation are clearly seen in all the large river-valleys of 

 Canterbury. High up on the mountain-sides are seen the terraces with 

 their decided slope outwards from the mountain-axis. In all the valleys 

 roches moutonnees are abundant, and are deeply scored with glacial marks. 

 Smoothed rock-surfaces are to be found on every side. These features 

 have been observed and noted by every geologist who has wandered into 

 any of the great valleys. Marshall and Speight have advocated the idea 

 that the glaciers which filled the valleys are also responsible for the over- 

 deepening which these valleys have evidently undergone. In Canterbury it 

 is recognised that the larger glaciers crept through the present gorges into 

 the plains, and that their terminal faces were outside of the- mountain 

 regions. Such elevations as Woolshed Hill and Little Racecourse Hill are 

 considered to be portions of the terminal moraines. Only one locality is 

 yet known where the ice approached the east coast : this is at the Taieri, 

 where the well-known moraine extends for some six miles north-east and 

 at least ten miles south-west of the gorge of the river, and stretches three 

 miles east from the plains. 



On the west coast the glaciers then, as now, extended to far lower levels 

 than on the east coast. Ice filled all the profound valleys of the western 

 sounds, and in them ice-worn surfaces of rocks, roches moutonnees, glacial 

 cirques, hanging valleys, and all the other features of glacial erosion are to 

 be seen in perfection. 



