178 Transactions. — Geology. 



in the South Island, but only huge deposits of shingle cand 

 sand which may well have been derived from glaciers in the 

 mountains. Among the older of these are the Moutere Hills, 

 in the Nelson District, the Mount Grey downs in Canterbury, 

 and the shingle-beds under lava-streams at Timaru. 



Secondly, since the culmination of the glacier period 

 several important changes have taken place in the physical 

 geography of the country. The gorges of the Kawarau and 

 Dunstan, as well as those of the Mataura and Upper Taieri, 

 in Otago,* have all been cut, as have also those of the South 

 Ashburton and the Waimakariri, in Canterbury. Also several 

 of the older lakes have been completely filled up, as, for ex- 

 ample, those of the Eakaia and the Waiau-ua ; while others 

 — such as Lake Heron, Lake Tekapo, and Lake Pukaki — are 

 approaching their end ; all of which implies a long time. We 

 thus see that both kinds of evidence place the great glacier 

 epoch in the Pliocene period ; and if it should turn out to be 

 true that no older Pliocene marine beds exist in New Zealand, 

 then we may confidently place the greatest extension of our 

 glaciers in the older Pliocene, when both Islands stood higher 

 than they do now. If, however, it should be found that older 

 Pliocene marine beds connect the Miocene with the newer 

 Pliocene in the North Island, then we should have to assume 

 that the South Island alone was elevated in the Pliocene, and 

 that the great glacier epoch may have lasted through the 

 whole of it. However, I think the first supposition to be the 

 more probable. 



Pleistocene Period. 



During the Pleistocene period the great volcanoes of 

 Tongariro, Ruapehu, and Mount Egmout emitted andesite 

 lavas, while basalts were erupted in the neighbourhood of 

 Auckland and near the Bay of Islands. 



The old swamps, or lakes, in whicli such a large quantity 

 of moa-bones have been found, also belong to this period, and 

 as they have attracted much attention a word or two in 

 explanation may be interesting. At the time when these large 

 deposits of bones were being formed the climate of New Zea- 

 land seems to have been different from what it is now. This 

 was probably due to a greater eccentricity of the earth's orbit ; 

 for then, when our winter happened in aphelion, long cold 

 winters would be followed by sliort but hot summers. Tlie 

 heavy snows which fell during the winter would be rapidly 

 thawed in the spring, with the result of producing heavy 

 floods. This was our diluvial epoch, which followed the great 

 glacier epoch. 



• "Report on the Geology of Otago," Dunedin, 1875, p. 94. 



