THE CHARTOGRAPHERS OF THE STATION 



193 



to a glorious green. This change from indigenous vegetation, rooted in 

 grit and humus, to absolute nakedness from nakedness to a dense 

 turf of alien fodder - plants could only have occurred in the early 

 years of the run, during a period when the station was but slenderly 

 stocked. It is another example of what has been already noted, that 

 many of the small phenomena registered in this volume have been 

 possible only by a combination of many special factors, some of them, 

 moreover, of brief duration. Hill-tops, for instance, heavily stocked, 

 would have become rapidly enriched, the seeds of clover and grasses 

 dropped in the animals' manure would have immediately germinated, 

 and a matted turf been created within a few weeks that would have 

 resisted alike the trampling of stock and the wear of summer gales. 



Sheep viaduct. 



He, therefore, who may in the future interest himself in natural 

 phenomena, " my second self when I am gone," will know that al- 

 though all tops may then be of a similarly luxuriant green, yet those 

 sans pumice grit and humus have at one period been bare, naked wind- 

 blows. 



Another physical change on the surface of Tutira has been the 

 growth of ovine viaducts. They also are dependent upon a multi- 

 plicity of special conditions. The ancient plateau system of the run, 

 the varying elevation of its existing fragments, its attrition by earth- 

 slips and rain-storms, have been explained. In the course of time 

 sections from which the cap of limestone has slid away have become 

 mere ridges linking together narrow blocks of higher land. There are, 

 moreover, here and there throughout the whole of Tutira, those narrow 



O ' 



connections running east and west which have been called junctioning 



y 



