CHAPTER XVIII

Boundary of Fens.--Roman Works, Car Dyke, Sea Wall, Causeway.--Archipelago.--Littleport, Agrarian Riots.--Denver Sluice.--Roslyn Pit.--Fenland Abbeys, Chatteris, Ramsey, Peterborough, Thorney, Crowland.

The vast Fenland district of which the Isle of Ely is the core consisted, until the fens were drained, of an archipelago of scattered islets rising out of a morass, through which the rivers from the uplands around stagnated in a complex system of waterways, constantly changing, as one branch or another got silted up and the streams had to make themselves new channels.

The foreshore of the uplands may still be traced on a contour map, and is seen to be deeply indented, with bays running in from the fen and capes running out into it. The southernmost point of the morass was at Fen Ditton on the Cam, two miles below Cambridge. Its western boundary went by, Waterbeach, Cottenham, and Willingham, to Earith; thence through Huntingdonshire to Ramsey and Peterborough; thence, by Deeping, Holbeach, and Spalding, to the Witham, a few miles below Lincoln. Throughout all this length ran a Roman earthwork, the Car Dyke, still existing at many points, evidently thrown up by these mighty civilisers to keep the floods in check. A like Roman embankment, of much larger dimensions, is to be seen on either shore of the great estuary which of old brought the sea-shore as far south as Wisbech. The eastern boundary of the Fenland needs no such defence, as on this side the higher ground sinks much more abruptly to the fen level. It passes from Fen Ditton by Horningsea, Bottisham, Swaffham, and Reach to Burwell. Here a peninsula projects to Soham, followed by a deep inlet to Isleham and Mildenhall. Then it runs north and west to Downham, in Norfolk, and thence due north to the sea by Lynn.

We must not, however, suppose that the whole of this immense tract was always morass. Oscillations in the land level have more than once raised it high enough and long enough for great forests to clothe it; the trees of which, frequently of giant size, are constantly exhumed from the peat which the later depressions have formed over them.[233] The last of these forests seems to have lingered on into Roman times. A Roman roadway may still be traced, running east and west across the whole breadth of the district, from Denver, at the south-western point of the Norfolk uplands, to Stanground, near Peterborough, on the Huntingdonshire mainland. The Fens must have been very different from what they afterwards became for such a road to be in use. But before the collapse of Roman Britain in the fifth century of our era all seems to have gone to fen once more; and the islets in it served as a refuge for the remnant of the British population when the flood of the Anglo-Saxon Conquest burst over the land.[234]

[Footnote 233: See p. 196.]

[Footnote 234: See p. 168.]

These islets number some thirty and more, and vary considerably in size. Far the largest is that on which Ely stands, the southern part of which has been spoken of in