142 Peacock: Lincolnshire Naturalists at Frieston. 



swept away from Lincolnshire. The peats of the low-lying- 

 swamps since that time, for we have none older, have been the 

 best preservers of the records of our ancient^ forests and flora, 

 as the coal formed under similar circumstance was at an earlier 

 age. The Great Fenland in Lincolnshire, Cambridge, and 

 Norfolk supplies us with the fullest and most valuable evidence 

 as to the antiquity of our forest trees. Two beds of peat are 

 found in this great level. One lies on the Boulder Clay floor of 

 the Fenland, buried by sand and silt brought down from the 

 watersheds of the fen rivers, at a depth varying from 8 feet to 

 18 feet. The other is found above the silt wherever stagnant 

 water has collected on its surface. The upper and modern bed 

 contains late flint implements and signs of Roman occupation, 

 and may date back from 2,500 to 100 years, as the case may be, 

 but can hardly be earlier from the rate at which the silt has 

 been deposited, and the position in which the beds are found in 

 respect to it. The lower peat must have ceased growing - at the 

 time the brackish water of the Wash began to deposit the silt, so 

 we can easily assign an approximate date to the period at which 

 the lower peat bed ceased to be formed. Some idea of the rate at 

 which the silt deposits have taken place above it may be gathered 

 from what is now going on, and from the area of the land 

 which has been recovered from the sea during the last sixteen 

 centuries, for there is no reason to suppose the rate has ever 

 fluctuated much either way. The greatest accretion of land 

 from silting up has taken place at the head of the old Roman 

 bay at Briker Haven in South Lincolnshire. Here successive 

 enclosures have taken place from time to time, until the bank 

 made by the Romans at Holbeach, for the protection of their 

 corn land from the sea, is left from three to four miles inland. 

 Now granting, w r hich cannot be disputed, that these banks were 

 made from 1,500 to 1,600 years ago, it will be found that the 

 rate of growth has been about 9 feet to 10 feet a year. Allow- 

 ing the same rate of accretion in past ages as we find at present, 

 it would take 13,000 to 15,000 years for the formation of the 

 alluvial deposits of the present Fenland above the lower peat 

 stratum, which must have stopped growing before or at the 

 time the silt began to be formed. 



When trees are only found in the upper peat bed they may 

 be called modern, for they can only have been with us from 

 100 to 2,500 years, and may have come with the Romans. But 

 when they are found in both beds, above and below the alluvial 

 deposits, they have been growing and seeding in Lincolnshire 

 from 13,000 to 15,000 years. The species referred to here are 

 those growing in our woods and hedges to-day. 



Naturalist, 



