BRITISH POSTGLACIAL S- RECENT DEPOSITS. 449 



in which no trace of trees has been found. Not only so, but 

 similar seams of peat are observed interstratified again and 

 again with marine silt and clay. 



Shell- marl is also a deposit which occupies considerable 

 areas in the Fenland, and points to the former existence of wide 

 shallow lakes or meres. It abounds with the shells of such 

 genera as Pisidium, Planorbis, Limncea, Cyclas, Succinea, etc. 



Human relics and remains have been met with at various 

 depths in the Fen -deposits. These comprise, besides stone 

 implements of Neolithic forms, " dug-out " canoes. One of 

 these is said to have been of oak, and the tree out of which it 

 was fashioned was estimated to have contained 650 cubic feet 

 of timber. Eemains of the usual postglacial fauna are common 

 enough in some places, among them being Bos primigenius, 

 B. longifrons, fox, wolf, beaver, roebuck, red- deer, great Irish 

 deer, reindeer, otter, marten, wild-boar, and brown bear. In 

 the marine deposits occur the common seal, the Greenland 

 whale, the walrus, etc. But in none of the true Fen-beds has 

 any trace been discovered of the extinct forms characteristic of 

 Palaeolithic times. 



From the facts now briefly summarised the following in- 

 ferences may be reasonably deduced : — 



1st, The beach- and floor-gravels probably indicate an early 

 postglacial submergence ; but in the absence of marine remains 

 this cannot perhaps be asserted with perfect confidence. These 

 earliest deposits clearly prove by their position that a great 

 lapse of time supervened between the accumulation of the 

 Palaeolithic gravels of East Anglia, and the formation of the 

 true Fen -beds. The Palaeolithic and the Neolithic series are 

 not conformable ; the latter rest upon the worn and wasted 

 surface of the former. 



2d, At the base of the Fen-peat and silt there appears an 

 old buried forest, the position of which (30 feet below the 

 present sea-level) speaks to a former wider extent of land. The 

 climate was then favourable to the growth of trees ; by and by, 

 however, these conditions were changed — the forest decayed and 



2g 



