THE GEOLOGY OF ORKNEY. Ixxxix 
peat, the former swathing the irregular surface of the 
hills often right to their tops, while the latter occurs 
in flattish depressions which were at one time swamps 
or luchans. Hill-peat varies in thickness up to about 
six feet, but the bog-peat may be thirty feet or more 
in depth. Apart altogether from artificial interfer- 
ence, such as drainage, cultivation, and digging for 
fuel, it is clear that in many places the peat is 
wasting away by natural processes. This is well 
seen on the hill-tops, such as Wideford Hill, where 
the peat is worn and channelled, and the stones are 
peeping out through a thin and broken covering. On 
the summit of the Ward Hill of Hoy the bare stones 
are everywhere visible, and there are only thin scraps 
of peat. Yet there can be little doubt that at one 
time these places were covered with several feet of 
peat deposit. On the Harray Hills the summit peat 
iz rent and torn with great open “hags” or channels, 
and in dry weather the peat crumbles down and is 
blown away by the wind. Similarly, near exposed 
cliff faces, as in Westray and Sandwick, the peat is 
always removed for a considerable distance from the 
margin of the cliff. This is due to the action of wind 
and sea-spray. Clearly, then, the present geographi- 
eal and climatic conditions are not the same as those 
under which the peat was formed. 
REMAINS OF PLANTS FOUND IN PEAT 
STRATA. 
No investigation of the geology and botany of the 
Orkney peat has yet been made, such as Dr Crampton! 
1 C, B. Crampton, ‘‘ The Vegetation of Caithness,” 1912. . 
9 
