L 
ON REMAINS OF INDIGENOUS WOOD IN ORKNEY. 175 
time picked up, which are referred to a period prior to the Roman occu- 
pation. Several such forests have also been found in Scotland, two of 
which are in the county of Fife : one situated at the entrance of the 
Tay, and another at Largo in the Firth of Forth ; and I see that at a 
late meeting of the Field Naturalists' Society there, specimens of wood 
from the submerged forest of Largo Bay were exhibited. 
Geologists and other scientific men have propounded different 
theories to account for the existence of submarine forests. By some 
they have been ascribed to the agency of rivers or tides, carrying along 
m their eddies fallen trees and other estuary detritus, and massing 
them together just as sand banks or gravel banks are formed ; others 
helieve that they are occasioned by the sea encroaching upon low flat 
land, breaking through the coast barrier, and thus permanently en- 
gulfing the forest ; some view this encroachment as a gradual process 
going on at the present day in certain places ; others refer these phe- 
nomena to the drift or glacial period. 
these theories being somewhat conflicting and unsatisfactory, I was 
lately induced to give the subject some attention when in Orkney, sur- 
rounded by ample materials for investigation ; and although it may 
not be easy to account for the presence of trees in such unusual situa- 
tions, there seems good reason to assign a very remote antiquity to 
those found in Orkney. 
Our inquiry is both narrowed and simplified at the outset by the 
tact that (with the exception of the island of Hoy, where bushes of 
mountain ash, birch, and aspen poplar, are found in some sheltered 
nooks) no natural wood now grows in Orkney, nor is there any re- 
liable account of trees having existed there in former times. 
Barry, a modern writer, mentions a vague tradition that the harbour 
°f Otterswick, in the island of Sanday, was once a forest, which was 
destroyed by an inundation ; but I am inclined to think that the tra- 
uitioiij if such it be, has arisen from the fact that remains of trees have 
often been found in the bay. Any temporary inundation would, after 
a time, subside naturally, and leave the land exposed and dry as be- 
fore, unless the level in the interior was below high-water mark ; in 
^vliich case, from the swampy nature of the ground, it would be a most 
unlikely place in which to find trees. Otterswick Harbour is a bay 
w ith a wide entrance, having a surface of five or six square miles, and 
a depth of water sufficient for vessels of considerable tonnage; it seems 
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