Park. — The Great Ice Age of New Zealand. 599 



shorn Whakamarama Range ; the domed crests of Lead Hill and Mount 



Olympus ; the beautiful roches moutonnees at Boulder Lake — itself a perfect 

 rock-basin ; and the glacial drift scattered over the Aorere Valley, afford 

 conclusive proof that the Pleistocene glaciers of the South Island reached 

 as far north as Cook Strait in latitude 41° S. 



But Pleistocene glaciation was not confined to the South Island. There 

 is abundant evidence that a large portion of the Province of Wellington 

 suffered intense glaciation in that period. In the month of July of this 

 year I examined a portion of the Rangitikei Valley and country lying 

 around Mount Ruapehu. When I examined this region in 1886-87 it was 

 covered, except in the Inland Patea and Murimotu plains, with a dense, 

 almost impenetrable, forest, with few tracks or means of access. The 

 construction of the Main Trunk Line Railway, the spread of settlement, 

 and the clearing of the forest now render the examination of the topo- 

 graphy and geology comparatively easy. 



From the slopes of Ruapehu and Kaimanawa mountains the country 

 is occupied by soft marine blue clays of Pliocene age, containing a thin 

 band or two of rubbly shelly limestone. The surface of these rocks has 

 everywhere the distinctive features of a land-surface subjected to ancient 

 glaciation. The smooth, flowing outlines, the hummocky and mammil- 

 lated valley-bottoms, the truncated crests, the terraced slopes, are always 

 present. 



The Rangitikei is a U - shaped glacial valley, as also is that of its 

 tributary the Hautapu. The south and west slopes of Ruapehu are 

 drained by the Wanganui and Wangaehu rivers ; but it is obvious that a 

 stream of ice no less than 4,000 ft. or 5,000 ft. thick flowed from the Karioi 

 Basin across the divide into the Hautapu Valley, joining the great glacier 

 that filled the Rangitikei Valley, a few miles south of Taihape. 



The course of the Hautapu glacier is marked not only by the charac- 

 teristic erosion of moving ice, but by the sheet of volcanic debris spread 

 along its course for a distance of nearly thirty miles. The debris is mainly 

 composed of erratic blocks of various andesites transported from the slopes 

 of Ruapehu. It varies from to 60 ft. thick, as seen in the railway 

 cuttings ; and surmounts the hills and ridges bounding' the old glacial 

 valley, forming a more or less continuous sheet, everywhere resting on a 

 deeply eroded surface of the underlying marine clays or papa. Near 

 Ruapehu — that is, in the Karioi Basin — the till is mainly composed of 

 clays, blocks of andesite being absent or seldom numerous ; but after 

 crossing the divide into the Hautapu the blocks or boulders become more 

 and more abundant, until in the lower twenty miles of the valley they com- 

 pose the bulk of the till. Below Taihape they become less and less nume- 

 rous, and are seldom seen as far down as the jimction of the Hautapu and 

 Rangitikei. The blocks are always angular, and vary from small pieces 

 up to masses 6 ft. and 8 ft. in diameter. The largest blocks are more 

 numerous at the southern limit of the deposit than elsewhere. 



In many places the Hautapu has cut its way through the glacial drift 

 into the underlying papa, and in the progress of this erosion has formed 

 beds of resorted andesitic gravels that are well exposed on the banks of 

 the main stream near Turanga-a-rere and other places. These gravels also 

 contain well-worn greywacke pebbles brought down by the branches of the 

 Hautapu that reach northward to the Kaimanawas. The difference 

 between the tumbled rubbly glacial sheets of angular andesite blocks lying 

 over hill and dale, and the recent gravels derived from it by erosion, is so 



