If you are familiar with conventional wisdom about the making of the broads, you will be expecting a quotation like this.
Lambert, Jennings and Smith, 1965
Peat digging interfered with the growing of a great variety of staple raw materials, needed in everyday life. Deep digging permanently destroyed valuable, productive fen land. So it was strictly confined to specific areas known as turbaries. To ensure fair shares for all, the turbaries were divided up (much the fairest share going to the lord of the manor). Lower down the feudal pecking order a share or 'dole' consisted of a long strip running right across the area of fen designated as turbary; the smallest doles for the lower orders would have been the narrowest. All doles were allocated to individuals, and could be passed on by inheritance.
Some broads were dug much deeper than others. The deepest, Fritton Lake, was perhaps as much as seventeen feet, the shallowest, like Sutton Broad, only four. Joyce Lambert, working with Joseph Jennings (a Geomorphologist from the University College of Leicester), brilliantly demonstrated a clear correlation between the depth of a broad, its proximity to a river and the stratigraphy of the intervening fen. Whatever their depth, the bottoms of the broads are unnaturally flat.
From all of which we can conclude firstly that there was a practical limit to the depth, depending on where a turbary was situated, and secondly that everybody always dug down to that limit. With peat effectively rationed by surface area, the real answer to the question, "Why did they dig so deep?" seems pretty obvious. In order to make the most of their limited allocation, they extracted the maximum possible volume of peat from the minimum area of fen by digging down as deep as they possibly could.
No doubt the superior quality of the deeper, brushwood peat was a great bonus and may well have influenced the choice of sites for turbaries. But the fact of the matter is they would have dug down as deep as possible even if the peat had not been of superior quality.
What really motivated the makers of the broads was not the quality of the peat but a need to maximise extraction from a given area. This slight misconception has contributed to another one (and is perhaps only of significance for that reason).
Dredging.
There is clear evidence from 14th and 15th century records that, in addition to digging turves, they also dredged up peat in bulk from under water. It was ferried by boat across flooded diggings to the edge of the turbary where it was unloaded. It was then subjected to a rigorous process by which it was mashed with water, pressed flat, shaped, dried, and finally cut into useable turves.
As I told you in part 1, Clifford Smith assumed that these dredging operations were only undertaken when flooding of a formerly dry turbary had made digging impossible.
George, 1992