THE DRIFTS OF SOUTH-WESTERN ESSEX. 175 Sturry that rafts of older deposits, enclosing contemporary implements, have been transported bodily into gravels of late date, and this process may also have occurred here. The Ilford Brickearths (10-40 O.D.) [Hinton 1900].—These classical deposits fit appropriately, alike in fauna and position, between the Furze Platt and the Crayford stages. The Northfleet Stage (30-40 O.D.).—The river erosion platform stands at about 30 O.D., and appears to represent a pause in the down-cutting between the 50-foot platform and the Crayford stage. This floor is occupied by an Early Levallois industry, and it is covered, not by river deposits, but by a sludge stream of Coombe rock, or chalky rubble, which indicates sub-glacial conditions. The name site of the Taplow Terrace appears to be of this stage. The Crayford Stage (— 10? to +50).—This was preceded by emergence with down-cutting by the rivers so that the erosion floor, or river-bed, appears to descend below O.D. The river fore-shore at 0 to 30 O.D. was occupied as a working site of the Mid Levallois industry [Spurrell 1880, Chandler, 1912, 1914]. Similar flints are also found in the lower part of the brickearths, which are banked against a buried river cliff. The Crayford deposits consist, in ascending order, of :—L Basement gravel ; 2. Lower brickearths ; 3, sandy shell-bed with Corbicula fluminalis ; small mammals, etc. ; 4, upper water-laid brick- earths up to about 50 O.D. ; 5, Trail. The shells of No. 3 indicate a warm temperate climate, but the small mammals (Spermophilus, etc.) indicate a cold fauna. It was probably a time of changing climate, and there may have been a land surface above the shell bed from which the small bones were introduced by burrowing animals. Two years ago I described to you the way in which large numbers of small bones were introduced by badgers into the glacial sands at Nettleswell Cross. On our side of the Thames, at West Thurrock, a similar section is revealed in a tramway-cutting to a chalk pit. There is the Mid Levallois working site on the old foreshore, which is inclined from the foot of the buried river cliff towards the bed of the river, and this is similarly covered by the loamy and sandy river deposits that are aggraded up to about 50 O.D. The alternate emergence and submergence of the Clacton stage is repeated, and at Crayford there is again evidence from the shell fauna of brackish water conditions up to about 30 or 40 O.D., thus leaving deposits belonging to different stages over the same range of levels.