Canterbury and Westland. 399 



more so when we consider their volume was so greatly reduced. It 

 is thus now easily understood that, for instance, the post-pliocene fan 

 of the river Ashburton was so enormous, and that as the then glaciers, 

 all assisting in the formation of these large deposits, shrunk back to 

 their proper valleys, the outlet from the one remaining Ashburton 

 glacier does not stand in any relation with its former fan. Conse- 

 quently it has not been able to lower its channel to any extent, whilst 

 the Eakaia, which is still the outlet of considerable glaciers, and has 

 retreated much more than the former, has been able to cut its channel 

 much deeper, and to prepare a much more uniform gradient for its 

 bed. 



As the mountains began to become gradually eaten into by the 

 action of the descending ice-masses, sharper ridges and peaks were 

 formed, so as to lessen the extent of the surface where perpetual 

 snow could accumulate to feed those glaciers, which consequently 

 began to retreat. Therefore the sources of the rivers which now cross 

 the plains were lying, in the post-pliocene epoch, much nearer to the 

 sea, their fans were much steeper, and they continued to build them 

 higher and higher, changing their apex continually, and at the same 

 time forming with their lowest portion the shore line of the ocean. 



All my observations show at the same time that the three great 

 post-pliocence torrents, namely, the Ashburton, Eakaia, and Eangi- 

 tata were united without doubt in one large water-course before they 

 reached the sea, having a common fan at their mouth, following the 

 law that rivers which unite, endeavour to do so by the shortest line. 

 This fact is well illustrated near the present mouth of the river 

 Hinds. This river flowing between the fans of the Eakaia and 

 Ashburton above the point where they united into one, has been 

 forming a swamp of considerable extent, being four to five miles 

 broad and eight miles long. It has partly been drained by natural 

 water-courses, partly by artificial drains under process of formation, all 

 passing through the higher shingle beds in front. The united existence 

 of such a fan is also instructively shown at the coast, where the sea 

 has worn away the protruding arc between the southern bank of the 

 Eakaia and the northern bank of the Eangitata. These cliffs, con- 

 sisting of true river shingle and river sand, are at the south side of 

 the Eakaia about six feet high, and rise gradually to an altitude of 

 70 feet near the mouth of the Wakanui Creek, four miles north of the 

 Ashburton river, where consequently the united fan has suffered the 

 greatest destruction. Having reached this altitude the coast cliffs 



