248 Geology of 



Banks' Peninsula, that a long period of time was necessary before that 

 volcanic system, as it now appears, conld have been built up, there 

 being at least three well-defined series erupted one after the other ; 

 in each case, the former craters having been partly destroyed before 

 the new ones were formed. "We have no fossiliferous beds in the 

 neighbourhood to guide us as to the time when these volcanic eruptions 

 took place, but I think that they occurred at the close of the Pareora 

 formation, when the country rose again to, or above, its present 

 level. Towards the end of the pliocene period, the country had 

 nearly assumed its present form, but the mountains were higher and 

 more plateau-like ; the valleys not so deep and wide, and moreover, 

 extensive cretaceo-tertiary and tertiary strata were lying on both sides 

 of the high alpine ranges, often blocking up the valleys, or covering the 

 lower regions with their deposits. The Great G lacier formation of 

 New Zealand now made its appearance, the effects of which upon the 

 configuration of the country were of great importance. The whole 

 plateau-like central range was covered with enormous masses of 

 perpetual snow, from which gigantic glaciers descended by every 

 opening to lower regions, and which have left ample traces, of striking 

 appearance, in all directions, on the "West Coast for some hundreds of 

 miles along the coast ; on the East Coast descending as low as 700 

 feet above the sea level. We may say that even at present we are 

 not yet at the termination of that period, the great glaciers, which 

 have now retreated so far back amongst the ranges, after repeatedly 

 advancing again, still continuing their work of destruction, the rivers 

 which issue from them extending the plains along the sea shores of 

 both coasts, whilst inland they excavate or raise their valleys and fill 

 up lakes through which they flow. Along the sea coast sand dunes 

 are still being formed, by which the land gains upon the ocean, 

 whilst in other localities it is destroyed and the sea takes its place. 

 And now, man, by his engineering works along the coasts, and at or 

 near the mouths of rivers, by destruction of forests and virgin vegeta- 

 tion, by draining swamps, by planting trees, and other works necessary 

 for the colonization of a country, also brings about material changes 

 which, although at present scarcely visible, will be of the utmost 

 importance in centuries to come, altering, or at least modifying, some 

 striking physical conditions- of the country. 



