Contribution to Vertebrate Fauna of West Ross-shire. 385 
become masked by a thin covering of peaty soil, thus pro- 
ducing a succession of shallow, trough-like hollows. In wet 
weather the water is prevented to a great degree from 
following the natural drainage lines, owing to the fact that 
these hollows lie across the general slope of the ground, 
They thus become completely water-logged, and after two or 
three days of rain the only dry spots over large areas will be 
the tussocks of coarse grass that rise above the sodden ground. 
In a region of such excessive rainfall this may well account 
in great measure for the scarcity and stunted character of the 
heather over a large extent of the district, and consequently 
affect the number of the birds that depend upon heather for 
cover and food supply. To the same cause may be attributed 
the scarcity of such birds as the Curlew, Golden and Green 
Plover, Redshank, and other waders on these moorlands in 
the breeding season, a scarcity in striking contrast with their 
abundance on the drier hillsides of the Central and Eastern 
Highlands. 
2. Cambrian Zone. —The Cambrian rocks form a belt, 
usually not more than a mile or two in breadth, that extends 
from Ullapool on Loch Broom to the heads of Lochs Kishorn 
and Carron. The principal member of this series is the white 
quartzite, which is seen capping most of the higher mountain 
tops along the line from An Teallach to Ruadh Stace in 
Strathcarron, and reaches its greatest development in Ben 
Kighe, whose bare glittering scree-slopes and serrated ridges 
form one of the most striking features in that wonderful 
panorama of loch and mountain which opens to the view 
from the head of Glen Docherty. This quartzite is a very 
siliceous, hard, and splintery rock. It breaks up into large 
angular fragments, produces little or no soil, and is therefore 
inimical to plant and animal life. In fact, no mountain tops 
are so utterly barren and lifeless as those covered with the 
Cambrian quartzite. Yet it is amongst the tumbled screes, 
composed of angular blocks of all sizes, which skirt the 
highest quartzite peaks, that the Snow Bunting is to be 
looked for in the breeding season in West Ross; and it may 
well be that among these scenes of desolation the bird finds 
the nearest approach to the arctic solitudes it loves so well. 
