Great Level. 



91 



In the clay with gigantic fallen trunks beside them, all covered 

 by the moor ; thus affording some criterion of the sites and mag- 

 nitude of the forests which clothed this region before that stu- 

 pendous catastrophe occurred by which they were cast down and 

 overflowed by the waters; their leaves and branches decaying, to 

 form a protective covering over the huge trunks. 



In some places a second bed of peat, with plants, &c., still 

 decaying, is found beneath 10 or 12 feet of clay, thus showing 

 the former surface of the earth, with a stratum the deposition of 

 ages resting upon it.* The tract of peat land extends from near 

 Cambridge, through Ely, March, Thorney, Crowland, Spalding, 

 and Tattershall, to Lincoln; in length being about 80 miles, and 

 varying greatly in breadth, though the average may be about 10 

 miles. The greatest breadths are those from Ramsey to Down- 

 ham, 24 miles ; from Peterborough to Wisbech, 18 miles; and 

 from Bourn to Spalding, 9 miles. But this black fen land is not 

 continuous, being intercepted by alluvial soil deposited by the 

 rivers which pass through it ; and towards the surrounding hills 

 and in many other parts, broken by hi^h lands (which were 

 doubtless the fruitful islands that once adorned the Fens) con- 

 sisting of diluvial deposits of sand^ gravel, and clay, either separate 

 or mixed. Between this peat land and the sea is a level tract of 

 rich loam and salt marsh, extending from Lynn through Long 

 Sutton, Fossdike, and Boston, to Wainfleet, being in length 

 about 45 miles, and varying from 4 to 1 5 miles in breadth. 



The peat soil naturally produces a coarse grass not of much 

 value, and abundance of straw when under arable culture, but 

 very little grain, and that of a weak light nature. The land is 

 so porous and spongy, that it holds a great quantity of water, 

 rendering it (when badly drained) so wet and soft that it is im- 

 possible to walk upon it ; but, when well drained, it naturally 

 sinks down and becomes more firm ; and it is of the utmost im- 

 portance to keep the water as low as possible, such being the 

 absorptive power of the soil that it is always saturated with m.ois- 



* There can be little doubt that the clay found throughout all the fens 

 is a tidal deposit, probably washed down, originally, from the uplands 

 into the estuary, and by the tides taken up the rivers and creeks, which, 

 overflowing the whole surface, deposited;this stratum of soil, for sea-shells 

 have been found in it even at the depth of 140 feet ; and in the operation 

 of claying the old channels of creeks, &c. are found, with numbers of sea- 

 shells buried in the earth, the sides of the creeks being raw silt for 2 feet 

 above the clay on each side. The same buttery clay may be found above 

 a stratum of moor, which must be of great antiquity, as the bed (of moor 

 found 2 feet thick in making Eau Brink Cut) must have been a long period, 

 in forming from either a crowded field of vegetation, or a stagnant morass ; 

 and after it was formed the tides deposited 6 or 8 feet of clay, on which 

 (as shown in the Eau Brink Cut) the Romans made their embankments. 



