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Transactions. 



forms, as shown in fig. 1, where the soft clay is undercut, and in Pkite XLIX, 

 where a sharp spine-like point of clay projects into the overlying till. 



At the north end of the tunnel near the 251|-niile post there is a fine 

 exposure of the glacial deposit in a cutting about 8 chains long. Here, 

 as at the 250-mile post, the andesite blocks are mingled with many large 

 angular masses of soft Tertiary sandy clay torn from the adjacent bed-rock. 

 These masses of soft sedimentary material are quite angular, and so soft 

 that they could not have withstood even for a few yards the pounding 

 action of running water ; hence we are forced to conclude that they now 

 lie in the places where they were dropped by the ice. 



At the 252|-mile post there is a deep cutting in which the andesite till 

 is seen to overlie unconformably a series of stratified clays, sandy clays, 

 and loose gritty tufi-like beds composed of andesitic material, the exposed 

 thickness being about 50 ft. This stratified series is obviously of fluvio- 

 glacial origin. At its base it contains a tapering lens of fluviatile drift (6), 







°o 



o 

 6^ 



Q =: Oo 



: c- 



GS'- 



7j'. 



-> 



Fig. 2. — Section of Rallway-cutting (South Side) at 252-1^- mile Post, Three 

 Miles and a Half South of Tubanga-a-eebe. (Scale, 1 in. to 60 ft. ) 



a. Pliocene marine clays (papa). 6. Andesite gravel. c. Sandy clays with tuff-like 

 andesitic beds. d. Clayey beds. e. Irregular deposit of coarser andesitic grit 

 intercalated in sandy beds. /. Glacial boulder rubble or till. g. Yellow clays. 



the greatest thickness of which is 5 ft. The whole series is intersected by 

 a number of very distinct faults, some of which are shown in fig. 2. 



The faulting took place before the deposition of the upper andesite 

 rubble drift or till, as shown by the circumstance that the till rests uncon- 

 formably against the faulted ends of the stratified beds. Moreover, the 

 faults do not affect the till in any way. 



This evidence is of great importance, as it clearly points to the existence 

 of two phases of glaciation in the North Island during the Pleistocene. This 

 section is shown in fig. 2 above and in Plate L. 



The glacial till is well exposed in the railway-cuttings between the tunnel 

 at 252^ miles and Ngaurukeliu Siding, and between Mataroa and Taihape. 



