Spkicht, CocKAYNi;, Laino. — Mniivt Arrnirsttiifh DiKfrict. 359 



the atones are very liable to move downwards, considerable breadths of the 

 uppermost laver frequently slipping en masse. In some places there is 

 little finer soil, but generally there is a good deal of sandy debris, and not 

 infrequently a certain amount of sandy clay, especially at some distance 

 below the surface, where the ground is more stable. 



Although the stones are quite dry on the surface, at a depth of a few 

 centimetres they are damp, and lower still there is ample moisture available 

 for deep-rooting plants. 



Movement of the stones, the most important distinguishing feature of 

 the soil from that of fell-field, is much less near the sides of the shingle-slip 

 than elsewhere, and there sufficient stability is provided for plants other 

 than those of the true shingle-slip formation to settle down. 



The looseness of the surface acts as a " dry mulch " and prevents evapo- 

 ration from below. 



ft Climatic. 



The general climate is, of course, that of the district and the altitudinal 

 belt. The special climate depends upon lack of shelter, and consequently 

 great exposure to wand : strong radiation of heat from the stones ; powerful 

 heating of the stones themselves ; and occasionally very bright light. Within 

 the space of a few hours the plants are frequently subjected first to a burn- 

 ing heat and then to considerable frost ; one hour they may be surrounded 

 by a moist atmosphere and the next exposed to a strong dry wind. In 

 winter they are covered by snow for four months or more, but this covering 

 is of little moment to the summer-green herbs. Shortly after the snow has 

 melted the leaves appear above the stones, and even by the beginning of 

 November Veronica rpacridea may be in bloom. 



(c.) Fell-field. 

 * General. 



Warming's description of fell-field (1909, p. 256) might have been written 

 on a New Zealand dry mountain : " The soil is never completely covered 

 by plants. One individual stands here, and another there ; between them 

 we see bare, stony, sandy or clayey soil, which is devoid of humus and 

 determines the prevailing colour of the landscape." An English name was 

 much needed for this formation, previously called by Cockayne " alpine 

 meadow" (1900, p. 128), and a combination of "fell" = a barren or stony 

 hill, and " field " = a wide expanse, chosen by Groom as the English equi- 

 valent of " fjeldmark," seems to us to meet the case. 



Fell-field is poorly develoj)ed in many parts of the Arrowsmith district, 

 and forms patches or lines, oasis-like, in the desert of unstable stones. 

 It commences by a few plants settling on the stable margin of the shingle- 

 slip or where the stone-field happens to be flat, and as soil is slow^ly formed 

 so do the species increase in number, but never make here a closed forma- 

 tion. At its lowest limit steppe and fell-field merge into one another, and 

 are not distinguishable ; even to quite a high altitude occasional tussocks 

 of Danthonia flavescens are present. 



The following are amongst the earliest plants to occupy the stable 

 debris : Danthonia semiannulari^ var. setifolia, Acaena Sanguisorbae var. 

 filosa. PimeJea LyaUii, Epilobium sp. (formerly merged with E. conferti- 

 jolium) Hydrocotyle novae - zelandiae, Anisotome aromatica Gaultheria 

 rwpestris. Dracophyllum rosmarinifolium, D. unifoliiim., Pratia macrodon, 

 Phyllachne Colensoi, Forstera Bidwillii Brachycome Sinclairii, Celmisia 

 discolor, C. spectabilis, Helichrysum bcUidioides, and Cotula pyrethri folia. 



