Park. — Glacial Till in Eauta'pu Valley, Wellington. 575 



Art, LVIII. — On the Glacial Till in Hautapu Valley, Rangitikei, Wellington. 



By Professor James Park, F.G.S. 

 [jReac? before the Otago Institute, 10th August, 1909.] 



I WISH to bring under the notice of the Society some important evidence 

 of ancient glaciation I have recently discovered in the western portion 

 of the Province of Wellington. The general geological structure and physio- 

 graphical features of this region are as follows : — 



The triangular area lying between the Manawatu Eiver and Wanganui 

 is occupied by a gravel drift 400 ft. or 500 ft. thick. Along its inland 

 border this drift rests against a series of marine clays of Pliocene age that 

 are horizontal or dip gently towards the sea. These clays, which are 

 commonly known by the Maori name " papa," extend northward to the 

 flanks of the Kaimanawa Mountains, along their northern Hmit skirting 

 the upland plains that wrap around Euapehu. In a few places they are 

 intercalated with thin beds of shelly limestone, or contain irregular layers 

 of hard calcareous nodules. 



The gravel drift forms the coastal plain, which is now highly cultivated ; 

 but north of this the papa country is broken into hills and ridges, which 

 are covered with a dense forest. Inland of the forest-belt, which is forty 

 or fifty miles wide and runs parallel with the coast-line, the country is 

 undulating grass land. 



The Kaimanawa Mountains, from 4,500 ft. to 6,000 ft. high, are drained 

 by the Rangitikei River and its tributary the Moawhango ; and the papa 

 country, going westward, by the Hautapu, Turakina, and Wangaehu, the 

 first a branch of the Rangitikei. These rivers rise in the inland treeless 

 country, traverse the forest-covered papa lands, and all, except the Hau- 

 tapu and Moawhango, flow across the coastal plain, in which they have 

 excavated deep channels with vertical banks. The Wangaehu River drains 

 the south-east slopes of Ruapehu, from 7,500 ft. to 9,000 ft. high, rising 

 in the glacier occupying the crater of that mountain. 



Beginning at Waiouru, situated on the inland grass lands, and thence 

 proceeding eastward across the ridges dividing the W^angaehu from the 

 Hautapu, the hills are found to present the smooth-flowing outlines, trun- 

 cated crests, and terraced slopes characteristic of glacial erosion. Many 

 of the higher hills are domed, while the low hills are hummocky and whale- 

 backed in form. At Taihape the hills are beautifully rounded, coned, and 

 domed, and at Mataroa there is a fine example of a U-shaped valley. The 

 evidences of ice erosion are also conspicuous both in the upper and lower 

 Rangitikei. 



During a recent examination of this region I also found that a large 

 stretch of country, beginning at Karioi, near the foot of Ruapehu, and 

 extending across the dividing-ridges into the Hautapu Valley, was covered 

 with a sheet of glacial boulder-clay or till. 



The till consists of clays, or of clays mixed with andesite blocks, or of 

 andesite blocks containing little or no clay. It is generally unstratified, 

 but in a few places layers of boulders are interbedded with bands of clay. 

 The boulders range from small blocks up to masses 6 ft. and 8 ft. in diameter. 

 They are always angular or semiangular, the latter being the result of 



