ANTHELIA: AN ARCTIC-ALPINE PLANT ASSOCIATION 83 



matter as a sediment.^ The snow-water carries the dust 

 which gathers on lying snow, fine particles of mineral matter 

 and fragments of plants, and it also collects other materials 

 as it trickles over the surface. Snow-dust, according to 

 Ratzel, may contain 50 per cent, of organic matter, and as this 

 with the finely divided mineral matter is laid down amongst 

 remains of last year's vegetation, a rich soil is built up. The 

 soil is dark and finely fibrous and when lifted adheres 

 together as clods. On Lawers this turf contains numerous 

 particles of glittering mica, while other samples from Suther- 

 land show particles of gneiss. Brockmann-Jerosch points 

 out that this substratum owes its origin solely to the action 

 of snow-water and rain, and that the snow-flush vegetation 

 occurs where the snow-water collects, not necessarily where 

 the snow-patches lie longest. The substratum results, there- 

 fore, from slow sedimentation combined with growth of 

 vegetation which is not swept away but remains perennial, 

 rising gradually each year on the new sediment. This 

 building-up may be seen where a boulder or piece of rock is 

 present and becomes gradually embedded. On these grounds 

 we regard this habitat as migratory and comparable to the 

 flushes described by C. B. Crampton (2) ; the snow-flush 

 vegetation will, therefore, come under that author's group of 

 migratory plant formations. 



During spring the snow-flushes are soaking and their 

 moisture is retained far into the summer, hence in a moist 

 season they remain slimy and slippery underfoot. In a dry 

 summer (as in August 191 1) they become cracked and 

 crusted. Although it may be surrounded by a green sward 

 of Alchemilla alpina with arctic-alpine grasses {Festuca, Poa, 

 Deschampsia, Nardus), the snow-flush is mainly dark in colour 

 except where tufts of Gnaplialium supinum, the dark-green 

 mats of Salix herbacea, or moss-tufts of Polytridmin have 

 become established. 



The vegetation of the snow-flush begins with cryptogams, 



^ These characteristics suggest the term "snow-flush.'" The original definition 

 of "flush" by C. B. Crampton (2) is: ''Sloping ground gives rise to springs. 

 Where the springs are of small volume, or where they are of a temporary nature 

 flowing only in wet weather, the growth of plants prevents marked erosion of the 

 surface and shallow gutters floored with vegetation result. These may be called 

 'flushes.' The vegetation and plant association of these flushes depends on the 

 nature and source of the flow of water " (p. 62). 



