Haedcastle. — On tJie Drift in South. Cnntcrbur!/. 315 



really loess of the same kind whicli afterwards overspread so 

 much of the formation, i.e., -svind-blown dust. One of the clay- 

 beds related to the red gravels appears to be of this nature. It 

 underlies the dolcrite at Mount Horrible, and directly overlies 

 rearranged marine sands, at a spot which must always have 

 been above tha reach of rivers. The bnly doubt as to this 

 being a loess-bed is founded on the possibility of its being a 

 slope-deposit, or rain-wash, from some eminence which has 

 since been removed. 



The shingle is everyjvhere highly oxidized and much de- 

 composed. It is somewhat harder as well as coarser near the 

 hills ; but generally, and the smaller shingle everywhere, is 

 too rotten to be of any use for road-making. At Timaru, 

 pebbles whose smooth surface shows that they were once hard 

 enough to take a tine polish can now be cut v/ith a knife like 

 chalk. 



The great quantity of the red gravels implies a correspond- 

 ingly great denudation of tlie neighbouring mountains, from 

 which the material was derived, plus a liberal allowance for 

 finer material carried further away. The greater part of the 

 formation being of shingle is proof that frost was the agent of 

 denudation. Large deposits of river-shingle can only be pro- 

 duced in one way — by frost and thaw brealdng up the surface 

 of mountains steep enough to enable gravity to deliver the 

 spoil to streams sufficiently powerful to transport it so long as 

 their channels are confined and the fall great, but not power- 

 ful enough to transport it all when the fall is reduced and the 

 channels become indefinite. The form of deposit — except in 

 deltas, and these are not deltas — is necessarily the fan, modi- 

 fied, it may be, by the work of other streams or by obstructive 

 eminences. From my observations I conclude that in the red 

 gravels of South Canterbury we have the decomposed, dis- 

 turbed, and denuded remains of a coalescing system or sys- 

 tems of fans, laid down by small streams issuing from the 

 neighbouring low ranges, as the larger fans of the plains were 

 laid down by the larger rivers at a later date. 



Mr. Sandham Gillingham, who owns an osteite on the 

 Albury-Fairlie Creek downs, and who has paid much attention 

 to their formation, is also of opinion that those downs were 

 piled up by the streams which now intersect them. It ap- 

 pears, therefore, that at some time long subsequent to the 

 upheaval of the Pareoi'a sea-bed, a warm climate having pre- 

 vailed during the interval, a profound change of climate set 

 in, and King Frost began a long and vigorous reign, though 

 perhaps not continuous, whose history is writ large in'these 

 red gravels. 



The question now;to be asked;is : What degree of cold was 

 concerned in tlie production of these gravels ? Are they the 



