462 Transactions. — Geology. 



climate are found associated with those of a warmer climate 

 it has been generally assumed that a colder climate prevailed, 

 whilst the contrary must have been the case. Every basin 

 of accumulation must be considered in its flora and fauna as 

 representing a horizontal and a vertical area. Take, for 

 example, the deposits now going on in Hawke's Bay from 

 the Eivers Ngaruroro and Tukituki. These rivers carry down 

 to the sea the material from the whole of their drainage- 

 basins. Leaves from the slopes of the Euahine and Kaweka 

 Eanges will be mixed with plants from the warmer hill-slopes 

 bounding the Heretaunga Plain, just as the shingle and finer 

 rock-material from the one area will be mixed with the coarser 

 material from a different area at the spot where deposition is 

 most favourable. Now, when the deposits underneath the 

 Bay come to be raised, as they very probably will, the leaves 

 which have left their impressions on the finer sediment will 

 illustrate first a warm temperate climate, and second a climate 

 no less than 20 degrees lower than what we now enjoy in 

 Napier. But the verdict of the glacialists as read by their 

 interpretation of fossil life to-day would be that cold summers 

 and mild winters formerly prevailed in this district. Thus 

 Professor James Geikie, in his " Fragments of Earth-lore," 

 p. 265, says that " during one period of Pleistocene clement 

 winters and cool summers permitted the wide diffusion and 

 intimate association of plants which have now a very different 

 range. Temperate and northern species, like the ash, the 

 poplar, the sycamore, the fig-tree, the judas-tree, &c, over- 

 spread all the low grounds of France as far north at least as 

 Paris." 



But surely this is not dealing with the subject of the 

 geographical distribution of plants on lines which the study of 

 physical geography points out as necessary if we are to arrive 

 at a proper estimate of the work done by rivers in the matter 

 of erosion and reconstruction. My illustration might be carried 

 to an inland sea — the Mediterranean, where rivers such as the 

 Ehone and the Po from glacial areas and the Nile from a 

 tropical area pour their burdened waters into the same basin 

 of accumulation. By means of currents and gravity the 

 material from the different rivers will tend in the direction of 

 the deepest portion of the basin, and the floral representatives 

 from Europe and Africa will eventually merge or form parts 

 of the same continuous area of deposition. Thus the same 

 statement might be made with respect to the plant-impres- 

 sions from these areas as is now made with regard to the 

 Pleistocene period — that clement winters and cool summers 

 permitted the growth of tropical, temperate, and arctic 

 plants within the same area. Surely the fossil leaves and 

 plants, specimens of which are open for the inspection 



