Page:VCH Essex 1.djvu/50

 A HISTORY OF ESSEX fringe the marshes near Burnham. Again, in the western portion of the county, near Loughton, on Buckhurst Hill and north of Chigwell, there are gravels which it is exceedingly difficult to distinguish from neighbouring gravels on a slightly lower level which seem to form part of the true valley gravels. Some of these deposits may indeed represent stages in the denudation of the country which followed the recession of the ice-sheet. While the action of land-ice was partly to efface the old scenery by thick accumulations of Drift, it tended also to degrade and soften the bolder features ; but these to some extent have reappeared through the influence of subsequent denudation. The passing away of icy conditions, the melting away of the land- ice which enveloped so much of the ground, must have been attended by the formation of torrential streams which initiated the present lines of drainage. Along the Stour, Colne and Blackwater, and along the Lea and Thames, we find evidence of later Pleistocene gravels and brick- earths, to which attention must now be directed. Along the Crouch however we find no such ancient deposits. Rising in the hills of Lang- don and Billericay, it drains an area of London Clay comparatively free from the Glacial gravels, which in other valleys afforded material ready- made for the accumulations of valley gravel. The Crouch may indeed have existed in Pleistocene times, and have simply eroded without depo- siting much material along its course : but there is no evidence to show that this was the case. VALLEY GRAVEL AND BRICKEARTH The deposits of valley gravel and brickearth are old accumulations of the 'rivers and their tributaries, and they occupy grounds higher than the Alluvium, but often extend beneath it. The more important tracts of valley gravel and brickearth are those which occupy the Thames valley. They occur from Leyton and Strat- ford to Barking, Romford and South Ockendon, in a belt which in places is four or five miles broad, and rises 100 feet above the river. These deposits belong to the earliest system of drainage along the pre- sent valleys, and to a period when palaeolithic man co-existed with a fauna many of the members of which are either extinct or no longer inhabitants of this country. The mammalian remains have been met with in notable abundance at Ilford and Grays, not because these were exceptionally favoured places of entombment, but because the brickearth at Ilford and the Chalk below the brickearth at Grays have been very extensively worked, and for many years the remains were carefully looked after by the late Sir Antonio Brady at Ilford and by Richard Meeson at Grays. Sir A. Brady observed that the bones near Ilford were mostly found in the sands and gravels and in a very decayed condition, but they were better preserved in the brickearth. The chief locality was the Uphall 16