Seeley — Gravel and Drift of the Fenlands. 499 



Wisbeach St. Mary's, three miles west of the town, in a clayey bed 

 at a depth of fifteen feet, were found — 



Tellina obliqua, 

 Cardium edule, 

 Scrobicularia piperita, 



examples of which are preserved in the Wisbeach Museum, The 

 mammals of this clay are the Walrus and Grampus, and a large 

 Whale. The upper bed of peat is long anterior in date to the forma- 

 tion of Whittlesea Mere, seeing that it exists on the site of the 

 Mere, capped with two feet of gravel. The gravel and shell bed 

 below the lower peat are clearly marine. The Buttery-clay and 

 shells above that layer are also marine, while the erect position of 

 the trees show that the peat was not drifted, but clearly an old 

 land surface. Thus there is evidence of sevferal alternations of level 

 and different conditions of the country since the gravel. In the 

 upper peat Mr. Carter found a Bos primigenius slain with a large 

 chipped flint (of late aspect) which was driven into the brain. 



Nor would the fauna approximate the old peat period to the 

 present time. 



Bos frontosus, 



Bos primigenius, 



Cervus megaceros, 



are old peat species now extinct, which also belong to the gravel 



and cave deposits, 



Canis lupus. Castor Europeus, Sus scrofa, 



Cervus elapJms, Cervus capreolus, Lutra vulgaris, 



are Fen Fossils, which also occur in the gravel and caves of other 

 localities, though not near Cambridge. 



The only animal in the Fens which does not occur in cave or 

 gravel is JJrsus arctos. 



Other remains, such as teeth of hippopotamus and rhinoceros, may 

 have, been washed out of the gravel. 



A fauna is found in the uppermost gravel, which in preservation 

 would appear to be no older than this, whilst all the species seem to 

 be now living. 



4. Fine Grovels of the Plains. 



a. Physical considerations throw little light on the relations of 

 these deposits. The top of gravel is often undulated, and nearly 

 every gravel pit shows some indication of this darker layer, out of 

 which so often descend the structures called pipes. The flexures 

 have sometimes been attributed to coast ice, but from numerous 

 sections and observations on ground from which trees have been 

 removed, I believe that they merely mark the site of an ancient 

 forest. The bedding too may deceive. In a section of Potton 

 sands, at Potton, I was able to see the process going on by which 

 the beds were coloured. Between two oblique and comparatively 

 impervious bands of oxide of iron, there was loose sand, and 

 stretching over this in curves were films of colour evidently de- 



