A CLASSIC CASE OF CONFIRMATION BIAS
BILL SAUNDERS
The Origin of the Norfolk Broads - a classic case of Confirmation Bias
mallards
"Detailed evidence of the production of turf is confined, for the most part, to South Walsham, Hoveton, Martham and Hemsby, and Barton, together with a few statisitics from Suffolk for 1341. It extends from 1268 to the middle of the fifteenth century. It includes places where there are both side valley and by-passed broads. Conclusions based on such small samples must necessarily be tentative." Smith, 1960
(A complete schedule of all turbary related documents up to the end of the fifteenth century is available here. Records or groups of records which contain meaningful details are shown in bold typeface).
Over sixty broads were created during a period of at least three hundred years.
"The bulk of turf production went, one supposes, to feed local hearths and thus for the most part must have gone unrecorded." ibid.
The samples are indeed small.
No references to peat digging have survived from the eleventh century or earlier, the only document of relevance being Domesday in which much of the Broadland fen is described simply as 'meadowland', without mention of any turbaries.
From the twelfth century there is a handful of entries in the St.Benet's Registry (the earliest dated 1141), which tell only of the existence of turbaries, their approximate location, usually attributable to a specific broad, and of the nature of the title to them. There is nothing from the twelfth century to provide any clue to what method or methods were used to extract the peat, nor to whether excavated areas within the turbaries were dry or flooded.
With very few exceptions, the character of the small number of records which have survived from the thirteenth century is the same as the twelfth. The 'detailed' evidence to which Smith refers consists of non-continuous annual statistics for turf sales by the manor of South Walsham Hall starting in 1268 - and of very little else. There are, however, five (and only five) fragments, the earliest of which is in fact dated 1240, which provide direct evidence of the methods which were used to extract the peat; all five refer to turves being cut or dug, presumably with the traditional turf-spade or becket. Again, there are no records which provide any clues to whether excavated areas in the turbaries were dry or flooded.
Rather more documents have survived from the fourteenth and fifteenth centuries, the majority from the annual accounts of manors held by the Norwich Cathedral Priory, including the relatively numerous Martham Account Rolls, or from the Priory's own accounts. Most of the detailed references to peat production are concentrated in the first half of the fourteenth century. From the second half of the fourteenth century onwards, and after the ravages of the Black Death, the greater number of surviving documents provide fewer and fewer references to peat.
Starting in 1294, the Martham turf accounts are non-continuous. and contain one of the two earliest surviving references, both dated 1306, to a different method of producing turves, ("In scouring 1 lest of turves with the carriage of fen"); they also contain the earliest surviving clear reference to the presence of water in a turbary ("For the making of 2 lests of turf with ferrying"), dated 1312. The recorded cost of producing turves for home use in all Norwich Cathedral Priory accounts more than doubled between 1300 and 1310; it then fluctated, before dropping back in the early 1340s. Other sources provide the last surviving references to turves being dug (1390) and to other methods of peat extraction (1451) at sites where there is now a broad.
There is thus no evidence of the presence of water in any of the turbaries in the thirteenth or earlier centuries. Equally, there is no evidence of the absence of water in any of the turbaries in the thirteenth or earlier centuries.
The dearth, and thus silence, of early records is entirely consistent with either concept, proof of neither.
In addition to which:
"Much of the historical evidence bearing on the origins of the broads is circumstantial or indirect." Smith, 1960.

"'Circumstantial evidence is a very tricky thing', said Holmes thoughtfully. 'It may seem to point very straight at one thing, but if you shift your own point of view a little, you may find it pointing in an equally uncompromising manner at something completely different.'"
"The Boscombe Valley Mystery", Conan Doyle
Smith (1960) made his point of view absolutely clear:
"The stratigraphy and the form of the basins in which the broads lie suggest that the Norfolk Broads can only be the product of the large-scale extraction of peat, and then the subsequent flooding of the pits thus created [my italics] . . . ."
The most important tasks of the historical geographer are clearly, then, to establish the period over which the pits were being dug, the dating of the subsequent flooding, and the conditions under which the turf-pits were abandoned [my italics]. In addition, it should be possible to find cases in which the records throw light on the transition of a piece of land from turbary to broad."
As he embarked on his researches, Smith thus took it for granted that
For Smith, the silence of the early records, therefore, had to mean that all the turbaries were free of water. Because there is evidence that turves were being dug as late as 1390 in one turbary, while other turbaries had water in them, Smith could only conclude that the great, formerly dry pits had flooded one at a time rather than all at once.
"By Elizabethan times maps and other evidence show the existence of a number of broads. But there is no evidence at all that any of the broads existed before the beginning of the fourteenth century. On the other hand there is abundant record of turbaries and turf production from the twelfth century to the middle of the fourteenth." ibid.
Just as a broad is a great flooded pit, for Smith a turbary was a great dry pit.
Smith's interpretation of the historical evidence, in the round and in detail, is based on an assumption that, for the lengthy period of its creation, the basin of each and every broad was completely free of water, an assumption rendered highly unlikely by current knowledge of medieval water levels, and an assumption without positive support from documentary evidence.
What if you look at this same evidence from a different point of view? What if the broads originated as turbaries where small adjacent pits were dug out with turf-spades, each being left to fill with water as soon as it was completed? What if peat was dug from new, small pits, while parts of the same turbary were already permanently flooded?
"The Historical Evidence in Detail" HOME
Copyright 2009 The Medieval Making of the Norfolk Broads. All rights reserved.
The Origin of the Norfolk Broads - a classic case of Confirmation Bias
mallards