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 Chapter XII. At its extreme northern point, on a subsidiary islet of its own, is the large village of Littleport, chiefly memorable as having been the focus of a most serious agrarian outbreak, which in the year 1816 convulsed the district. Widespread agricultural distress marked the first decades of the nineteenth century. The wholesale enclosure of the common fields and the waste lands brought with it no small suffering to the peasantry; who everywhere lost, by the Enclosure Acts, the advantages which the waste lands had afforded them, receiving in exchange a scanty portion of "town land" in each parish, the rent of which is applied to local charities. And in many instances the policy of the Government placed these "town lands" in the least accessible corner of the parish; for the express purpose of preventing labourers from acquiring allotments in them and thus becoming less dependent on their wages. The draining of the fens, moreover, which was then in full progress, by exterminating the old abundance of fish and wildfowl deprived the marsh-men at once of their chief recreation and their most savoury food. Wages were only nine shillings a week, while wheat was no less than five guineas a quarter. These grievances actually drove the peasantry to arms, not without countenance from sympathisers of a superior class, who felt that the demand of the rioters for wages enough to purchase a stone of flour a week, which was all they asked, could not be called unreasonable.