"SENSE AND NON-SENSE."
How did medieval men manage to dig holes of such size and depth without drowning themselves? Here the evidence is sparse, patchy and circumstantial, the answer elusive.
The original thinking
To solve this and other non-botanical problems, Joyce Lambert obtained the help of some distinguished colleagues. Together they applied their common sense and decided on the most likely explanation: the broads must have been dug out as complete basins at a time when water levels were very much lower than they are now, only to become flooded subsequently when water levels rose. So they all went looking for the evidence to prove this theory right - with some apparent success.
It appeared that by around 1200 AD the east coast of Norfolk had risen to stand no less than thirteen feet higher above the sea than it does today, before, late in the 13th century, it had started to sink down again quite rapidly. This strongly suggested a long period when water levels in the rivers and fens inland would have been very much lower.
It looked as if the deep excavations must have started around 1100 AD. Judging from the few local records which have survived from those days, some of the huge pits had started to fill up with water around the beginning of the 14th century, a period well known for its great storms and floods. It seemed that once water got into a pit, although individual turves could no longer be dug up, it was still possible to recover peat by dredging for it; this bulk peat was then processed into useable turves. All the pits appeared to have become flooded by around the end of the 14th century as the rise in sea level continued; even dredging had ceased by the late 15th century.
This then formed the basis of the original concept of how the broads had probably been made. The only problem with it was the evidence from the fens themselves: inland water levels did not appear to have been anything like as low as the sea level. However, peat has peculiar properties. If you dig deep into wet peat, to well below the water table, it takes a very long time indeed for water to seep into the resulting pit from the saturated ground which surrounds it. Even so, the authors speculated that it might well have been necessary to keep the diggings dry with baling devices. However, they came to no conclusions on this point and the matter was left unresolved.
New evidence and current thinking
In the 1980s, undisputed evidence became available that throughout the medieval period both the sea level and inland water levels had in fact never been more than a metre or so lower than they are today. Modern authorities like Dr. Martin George have concluded from this that that the makers of the broads must indeed have used some sort of pump or baling device to keep the diggings dry. However, as Martin George himself very fairly points out, there is no direct evidence for this.
Clearly any rise in sea level has been much slower than originally supposed, and from a much higher starting point. In his wonderful book, "The Land Use, Ecology and Conservation of Broadland." (Packard, 1992), Martin George tells us that after several centuries of mild winters and warm, dry summers, the climate started to change towards the end of the 13th century, accompanied by great storms, floods and tidal surges. These factors must have prevailed over the measures being taken to keep the diggings dry, and one by one they filled with water and became unworkable. By the middle of the 14th century the climate had become much colder and wetter, and the remainder of the pits followed suit.