1 7 8 



Peacock : The Fenland Soils. 



a question whether there was a 'North Sea' during- the earlier 

 time of the formation of the Fenland basin. In Middle Tertiary 

 time, in all probability, Britain was joined to Norway by the 

 Orkneys and Shetlands, and to Iceland by the Faroes. In 

 Oligocene times the old Fenland river system, if it then 

 existed, must have drained into a southern sea, where France, 

 Germany, and the Netherlands are now situated. If we put the 

 Fenland basin denudation period much later, as I believe we 

 should, in late Pliocene times the detritus of the river would be 

 discharged many miles to the east of our present coast line into 

 what would be then a continental river rather than the ocean. 

 The Thames and Rhine would be other branches of this stream, 

 and the Fenland one of its middle height valleys. Certainly in 

 Pleistocene times, the forest period before the peat formation, 

 a large river only would be found where the North Sea rolls at 

 present. The only point for us to notice specially is that all the 

 material cut out of the Fenland basin was swept out of our area 

 completely. 



The Pleistocene, Quaternary, or Modern Period, began with 

 the increasing cold of Pre-Glacial time. When it reached its 

 local climax in the Chalky Boulder Clay Period of the Ice Age, 

 the whole of the Fenland basin was practically covered with 

 Boulder Clay, gravel, and sand, under a vast sheet of ice. The 

 ice stream came from the N.E. along the deepest part of what 

 is now the ocean bed. The north of England and Scotch ice 

 was deflected by the Scandinavian ice-stream, which lay still 

 further to the east, over east Yorkshire and the whole of 

 Lincolnshire. It came to us from the N.E. In the Chalky 

 Boulder Clay chalk predominates ; there is also much 

 Neocomian, but distant boulders are found from the N. of 

 England, Scotland, and Norway. They vary in proportion to 

 the nearness of the localities from which the supply has been 

 transported. The Boulder Clay is said to be 400 feet thick 

 at Boston, and at one time must have filled the whole basin of 

 the Fenland. It is now covered by thin beds of the Fenland 

 deposits of Pleistocene age except in a few spots. A geological 

 map of the Fenland shows no less than 17 islands of Boulder 

 Clay or older strata rising above the level of the true Fen beds. 

 In many cases they are capped with gravel of glacial origin 

 which represents former Boulder Clay. In Lincolnshire, 

 Stickney and Sibsey are instances, and on the south, along 

 with many others, are Thorney, Whittlesea, March, and Chatteris. 

 The Isle of Ely is so large as to enclose a big stretch of peat 



Naturalist, 



