Page:Submerged forests (1913).djvu/22

8 full of vegetable matter, showing sallows, alder, and hazel rooted in their position of growth. In this soil we may also find seams of shell-marl, or chara-marl, such as would form in shallow pools or channels in a freshwater marsh. This black peaty soil is obviously the same "submerged forest" that we have already examined on the foreshore at the mouth of the estuary; the only difference being that in the more exposed situation the waves of the sea have cleared away the overlying silt, thus laying bare the land surface beneath. In the dock excavations, therefore, the submerged forest can be seen in section and examined at leisure.

The next deposit (C), lying beneath the submerged forest, is commonly another bed of estuarine silt, extending to a depth of several feet and carrying our observations well below the level of low-water. Then comes a second land-surface (D), perhaps with trees differing from those of the one above; or it may be a thick layer of marsh peat. More silt (E) follows; another submerged forest (F); then more estuarine deposits (G); and finally at the base of the channel, fully 50 feet below the level of high-water, we may find stools of oak (H) still rooted in the undisturbed rock below.

As each of these deposits commonly extends continuously across the dock, except where it happens to abut against the rising ground, it is obvious that