Chapter XIII: Section IV

_Some further geological observations relating to the Fens_, _extracted from Dugdale’s Letters to Sir Thomas Browne_.

The fullest and most circumstantial account we have of these Fens is contained in Sir William Dugdale’s History of Embanking, the substance of which will be found in the following pages. He has also treated upon the same subject in his correspondence with his friend Sir Thomas Browne, published in the posthumous works of the latter; some extracts from which, being much to the purpose, shall be here submitted to the reader’s perusal.

In Letter IV, he says to his friend, “I shall here acquaint you with my conceit touching the spacious tract, in form of a sinus, or bay, which we call the great level of the fens; extending from Lynn beyond Waynfleet in Lincolnshire in length; and in breadth into some parts of the counties of Norfolk, Suffolk, Cambridge, Huntingdon, Northampton, and Lincoln: intreating your opinion therein. That it was at first firm land I am induced to believe, when I consider the multitude of trees (fir, oak, and other kinds) found in those drains and diggings which have of late years been made there.” After mentioning some instances, he adds—“Mr Goddard, Recorder of Lynn, assures me that lately in Marshland, about a mile from Magdalen Bridge, about seventeen feet deep (upon occasion of letting down a sluice) were found below the silt (for of that sort is all Marshland and Holland) in very firm earth, furze bushes, as they grew, not rotted; and nut trees, with nuts, not perished; neither of which kind of bushes or trees are now growing upon that silty soil of Marshland, though it be fruitful and rich for other vegetables.”—Afterward he adds, “I shall tell you how I conclude it became a fen by the stagnation of the fresh waters; which is thus—The sea having its passage upon the ebbs and flows thereof along the coast of Norfolk to the coast of Lincolnshire, did in time, by reason of its muddiness, leave a shelf of silt betwixt those two points of land, viz. Rising in Norfolk, and the country about Spilsby in Lincolnshire, which shelf increasing in height and length so much, as that the ordinary tides did not overflow it, was by that check of those fluxes, in time, so much augmented in breadth, that the Romans finding it considerable for the fertility of the soil, made the first Sea-banks for its preservation from the Spring-tides, which might otherwise overflow it. And now, Sir, by this settling of the silt, the soil of Marshland and Holland had its first beginning. By the like excess of silt brought into the mouths of these rivers, which had their outfalls at Lynn, Wisbeach, and Boston, where the fresh water is so stopped, as that the ordinary land floods, being not of force enough to grind it out (as the term is) all the level behind became overflowed; and as an ordinary pond gathereth mud, so did this do more, which in time hath increased to such thickness, that since the _Po-dike_ was made to keep up the fresh water from drowning Marshland on the other side, and South Eau-Bank for the preservation of Holland from the like inundation, the level of the Fenn is become four feet higher than the level of Marshland, as Mr Vermuiden assured me upon a view and observation thereof.”—Afterward he observes, “That the time when the passage of Wisbeach was so silted up, as that the outfall of the great river Ouse, which was there, became altered, and was diverted to Lynn, was in Henry the third’s reign, as my testimonies (says he) from records manifest.”

In his 5th Letter he says to his friend—“Since I wrote to you for your opinion touching the various course of the sea, I met with some notable instances of that kind in a late author, viz. _Olivarius Uredius_, in his History of Flanders; which he manifesteth to be occasioned from _Earthquakes_.”—And this appears to have become afterward our author’s own settled opinion, as to the ancient influx of the sea over this great level country.