When we turn aside into the areas cut off by spurs of gravel and islands of Jurassic rock, we find wide and deep masses of peat which has grown and been preserved from denudation in these embayed and isolated areas. Burwell Fen, for instance, protected on the north and west by the Cretaceous ridge of Wicken and the Jurassic ridge of Upware, furnishes most of the peat used in the surrounding district. If we travel about two miles to the north-west from the pit dug near the railway station (see Fig. 4, p. 11) over the hill on which Ely stands, we shall come to West Fen, where there is a great mass of peat which has grown in a basin now almost quite surrounded by Kimmeridge Clay. In this there is a great quantity of timber at a small depth from the surface. The tree trunks almost all lie with their root-end to the south-west, but some are broken off, some are uprooted, telling clearly a story of growth on the peat which had increased and swelled till the surface was lifted above the level of floods. Then some change--perhaps more rapid subsidence, perhaps changes in the outfalls--let in flood water, the roots rotted and a storm from the south-west, which was the most exposed side and the direction of the prevalent winds, laid them low. The frequent occurrence of large funguses, _Hypoxylon_, _Polyporus_, etc., points to conditions at times unfavourable to the healthy growth of timber. It is worth noting when trying to read the story of the Fens as recorded by their fallen trees that in all forests we find now and then a few trees blown down together though the surrounding trees are left. This may be the result of a fierce eddy in the cycloidal path of the storm, but more commonly it seems to be due to the fact that every tree has its "play," like a fishing rod, and recurring gusts, not coinciding with its rhythm, sometimes catch it at a disadvantage and break or blow it down. The story told by the West Fen trees is quite different from that told by the water-borne and water-worn trunks in the section by Ely station. The same variable conditions prevailed also in the more westerly tracts of the Fen Basin, but the above examples are sufficient for our present purpose. From the large numbers of trees found in some localities and from records referring to parts of the Fens as _forest_ it has sometimes been supposed that the Fens were well wooded, but forest did not generally and does not now always mean a wood, as for example in the case of the deer forests of Scotland. When Ingulph[5] says that portions of the Fenland were disafforested by Henry I, Stephen, Henry II, and Richard, who gave permission to build upon the marshes, this probably meant that they no longer preserved them so strictly, but allowed people to build on the gravel banks and islands in them. [5] _History of Croyland_, Bohn's edition, p. 282.