THE GEOLOGY OF ORKNEY. Ixxxv 
sank again to the fifty-foot level, where a pause 
ensued for a time; or that, after the epoch of the 
twenty-five-foot beach, the sea may have receded 
a long distance and subsequently returned to its 
present level, and many geologists believe that this 
was actually the case. 
BURIED FORESTS. 
The buried forests show that some such process 
has been going on. Beds of peat with stools of trees 
are known to occur at low-water mark and below it 
in several parts of the islands, eg., Westray, Skaill 
Bay, Deerness, and Sanday. Those who have made 
a study of these deposits are convinced that the trees 
and peat grew where they are now found, and this 
must have taken place on a land surface. Accordingly 
these buried forests establish that there was formerly 
a higher level of the land throughout the islands. It 
is impossible to make excavations in the sea-bottom 
except when the water is shallow, and consequently 
we have very little information as to the seaward 
limit of these forests. Where large docks have been 
excavated in some parts of England, it has been found 
that forest-beds occur 40 or 50 feet below low-water 
mark. We know also that trawlers dredge up peat 
and wood far out in the North Sea about the Dogger 
Bank. Facts like these lead us to suppose that at 
one time trees may have been growing far beyond the 
present boundaries of the land. At the same time we 
must not forget that this is only hypothesis, and is 
not yet, so far as Orkney is concerned, definitely 
proved. Mr Clement Reid supposes that the sub- 
