The Age of the Fen Beds.

Now we may enquire what are the limits within which we may speculate as to the age of the Fen Beds.

These Turbiferous deposits all belong to one stage, though it may be one of long duration. They are sharply separated from the Areniferous deposits, i.e. the sands and gravels of the terraces and spurs which always pass under and, in fairly large sections, can always be clearly distinguished from the resorted layers at the base of the Fen Beds.

There is no definite chronological succession which will hold throughout the Fens. The variations observed are geographical—clay, marl, peat, etc., alternating in different order in different localities and subaerial, fluviatile, estuarine, and marine, having only a changing topographical significance.

The Fen Beds crept over an area where the underlying formation had been undergoing vicissitudes due to slow geographical changes—changes which, being at sea level and near the conflict of tides and upland water, produced irregular but often important results.

There is not in the Fens any continuous record of what took place between the age in which the Little Downham Rhinoceros was buried in the gravel and that in which the Neolithic hunters poleaxed the Urus in the peat near Burwell.