Reviews — The Httrunui Valley. 523 



XI. — Structueal and Glacial Features of the Hurunui Valley. 



Bv K-. Speight, M.Sc, F.G.S. Trans. New Zealand Institute, 



vol. 1, pp. 93-105, 1917. 

 rpHE chief interest of this valley is that it is an excellent example 

 JL of a process of river development which is described by the 

 author, following Dr. Cotton, as " ante-consequent". The geological 

 history of the district is as follows: On an incompletely levelled 

 surface of grey wacke a series of Tertiary beds consisting of limestones, 

 marls, greensands, and conglomerates was laid down, the uppermost 

 of these being of Pliocene age. As these beds rose from the sea 

 a system of consequent drainage was established on the surface of 

 the land with sub-parallel streams running eastwards. When these 

 rivers had established their courses folding and faulting took place 

 along lines inclined at about 45° to the course of the streams. These 

 movements produced a number of parallel intermontane basins filled 

 with Tertiary rocks and separated by ridges of greywacke, and along 

 these basins most of the tributaries flow to the main stream. These 

 movements were of quite recent date and must have been very slow, 

 since though in the upper parts of its course the direction of the 

 stream is somewhat affected by them, in its lower reaches the river 

 was able to preserve the direction of its channel and cuts straight 

 through the greywacke ridges separating the basins along what must 

 have been its original line. In this respect the Hurunui River is 

 exceptional among the rivers of this region, since the courses of 

 similar streams to the north have been much disturbed by these 

 movements. 



In the succeeding Pleistocene glaciation the ice probably did not 

 penetrate to the lower portions of the valley, but the upper parts 

 were filled with glaciers and show evidence of strong ice action. On 

 the northern branch of the river, the ice, after arriving at the head 

 of a large lake called Lake Sumner, split into several distributaries 

 which passed over cols between the hills standing inside a right 

 angle formed by a bend in the course of the river. These cols have 

 consequently been lowered, partly by the cutting back of the corries 

 at the heads of the valleys running down from them and partly by 

 the ice streams flowing over them from above. Lower down at the 

 end of the eastern limb of the right angle these distributaries united 

 with the main glacier and were also joined by that from the south 

 branch of the river. 



W. H. W. 



XII. — The Geology of Banks Peninsula. By R. Speight, M.Sc, 

 F.G.S. Trans. New Zealand Institute, vol. xlix, pp. 365-92, 

 with 3 plates and 4 figures, 1916. 



BANKS Peninsula, which is situated nearly in the middle of the 

 east coast of the South Island of New Zealand, is a mass of 

 volcanic rocks about 25 miles long by 18 wide, projecting almost at 

 right angles from the coast. The surface is very hilly and rises to 

 a height of between 2,700 and 3,000 feet in several peaks. It is 

 bounded on the north, east, and south-east by the sea, on the west 



