as long as the barrier remains unbroken. The reason of this is obvious. The rise and fall of the tide allows sea water to percolate landward and the fresh water to percolate seaward; but the friction is so great as to obliterate most of the tidal wave. Thus the sea at high tide is kept out, the fresh water behind the barrier remaining at a level slightly above that of mean tide, and just above that level we may find a wet soil on which trees can grow. But, and here is the important point, a protected land-surface behind such a barrier can never lie below the level of mean tide; if it sinks below that level it must immediately be flooded, either by fresh water or by sea water. This rule applies everywhere, except to countries where evaporation exceeds precipitation; only in such countries, Palestine for instance, can one find sunk or Dead Sea depressions below mean-tide level of the open sea.
The submerged forest that we have already examined stretched far below the level of mean tide, in fact we followed it down to the level of the lowest spring tides. Nothing but a change of sea-level will account for its present position. In short, the three objections above referred to, while teaching us to be careful to examine the evidence in doubtful cases, cannot be accepted as any explanation of the constant and widespread occurrence of ancient land-surfaces passing beneath the sea.
