HuTTON. — On the Last Great Glacier Period in N.Z. 387 



of limestone and calcareous sandstone of upper-eocene age ; these rocks are all 

 planed down to a uniform level and covered by a tliin layer of silt and gravel, 

 which is at the same altitude as the thick gravel beds that form the other 

 parts of the plain ; the same thing on a smaller scale occurs in the Waimea 

 plains, in Southland, where the eocene limestone is also covered with gravel, 

 and cannot be distinguished in outline from the terraces ; we know of no 

 ao-ency but marine denudation that could effect this. The seaward plains 

 show their ori^-in still more distinctly by their uniform level all round the 

 southern face of the Hokanuis, and from the terraces being sometimes arranged 

 more or less parallel to the present coast. It is no objection to the marine 

 theory that beds of lignite are found under these deposits, on the contrary it 

 is much in favour of it, as it is well known that vegetable remains are very 

 sparinoly distributed in river alluviums, for they are scattered widely by the 

 currents, while, on the other hand, we know that most coal seams are covered 

 by marine beds. Indeed the occurrence of vegetable remains on a large 

 scale below alluvial plains is a certain proof that those plains were formed 

 either by lakes or by the sea, and not by rivers. These vegetable deposits 

 accumulated during the depression which preceded the elevation. 



Of the Canterbury plains I speak with much diffidence as I have not 

 visited them, and because Dr. Haast, after a careful examination, has come to 

 tlie conclusion that they have been formed by the rivers during a long course 

 of depression (Report on the Canterbury Plains, 1864), but judging from the 

 sections that he gives in his report I cannot understand how they can have an 

 entirely fluviatile origin, for in a line parallel to the coast they are nearly 

 level from the Waimakariri to the Rangitata, the highest portion being about 

 the Waimakariri. Now each of the rivers must have poured out an amount 

 of detritus proportional to its size, and therefore the plains should be higher 

 about the larger rivers than about the smaller ones ; but the fact is that the 

 country about the Hinds and Ashburton, two small rivers, is higher than that 

 about the Rangitata, a large river, and nearly as high as that about the 

 Rakaia, the largest river on the plains. If we suppose that the larger rivers 

 after raising their own beds wandered about the plains helping the smaller 

 ones, I can then see no reason why all the smaller rivers should have after- 

 wards left the common channel, and each pursued its own way direct to the 

 sea. Neither does Dr. Haast explain how it is that the gravel formation of 

 the plains wraps round the spurs of the hills at the same level that it has at 

 the river gorges, nor how it is that the plains of the Rakaia and Waimakariri 

 are nearly at the same level on each side of the Malvern hills, while the beds 

 of the rivers are at very different levels, nor why the tertiary rocks between 

 the junction of the Kowai and the Gorge hill, and at the gorge of the 

 Rakaia, are levelled on the top. Dr. Haast not only believes in a general 



