Haedcastle.— Oh the Drift in South Canterbury. S2S 



eruption, or rather at the time of the preliminary upheaval of 

 the gi'avels, and its appearance has scarcely altered from that 

 day to this. Curiously, tliis shingle and silt were not bunied 

 brick-red by the heat of the rock, as is the shingle elsewhere, 

 to a depth of many feet. I can only suggest that the porosity 

 of the then recent river-gi-avels allowed the moisture they 

 contained to be easily driven off as the heat of the lava made 

 its way down, so that when the bmning heat reached the 

 gravel, this being dry, it did not oxidize the iron in the stones. 

 This river-bed is based upon yellow fossiliferous sands. 



From the oxidation of the whole gi-avel formation, from 

 the decomposition of its sui-face into soil and subsoil, before 

 the lava overflowed it, and from the weathering |of the siu-face 

 of the lava before the loess 'of the second glacial period was 

 spread upon it, we must conclude that the " iuterglacial 

 period " of this hemisphere was of very gi-eat dm-ation, mea- 

 sm-ed even by geological standards of time. 



So far nothing has been said of the enormous amount of 

 denudation the red gi-avels have undergone since their dis- 

 tm-bance. Previous to disturbance, of coui-se, they would be 

 liable only to terracing by the principal streams flowing over 

 the fans. After disturbance, irregular elevation gave rise to 

 new di-ainage-hues, and steeper falls gave power to smaller 

 streams to perform excavating work. The red-gravel downs 

 have been enormously cut up, but it is more than probable 

 that the bulk of the work was done dming the second glacial 

 period, when these low giounds were undoubtedly glaciated. 



If the red gi-avels are admitted to be the record, in what 

 Professor Geikie calls a "peripheral area," of a glacial period 

 in the Southern Hemisphere, the climatic experience of Xew 

 Zealand corresponds with that of North America, where the 

 proofs have been recognised of two gi-eat glacial periods, sepa- 

 rated by a long interval of time, each of the glacial periods 

 being broken by shorter intei-vals of ameliorated climate ; 

 whilst our experience does not correspond with that of 

 Europe, where some observers recognise tlu-ee distinct au<l 

 separate glaciations in the Alps {vide Professor Geikie's presi- 

 dential address, Biit. Assoc, meeting, 18S9, on •• Glacial 

 Geology'). The discrepancy between the European and 

 American record can hardly be real, and may arise from a 

 greater value being assigned than should be, by the European 

 observers referred to, to one of the breaks in the earlier or 

 later glacial epochs. Similar breaks are registered in our red 

 gravels, and also in the products of the later cold age, as thev 

 ai-e in the Xorth American glacial beds. 



I trust that these statements and suggestions respecting 

 the red-gi-avel, or diift, formation, and its nearer chrono- 

 graphical relatives, will be found interesting and useful. I: 



