Cambridgeshire
The Corprolite Industry

Introduction

Cambridgeshire was also a place of industry, based on farming needs; its oddest industry was coprolite-digging, the extraction of phosphatised clay nodules for fertiliser. Coprolites occurred in a belt from Soham to Barrington and were exhausted in a rush between 1850 and 1890. It was an industry unique in England. Nodules were excavated in trenches, yielding 300 tons an acre.

The Discovery of Coprolite in Cambridgeshire

Why did coprolite production start at this particular time? There are two important factors to consider; partly the increase of geological knowledge and above all the accidental discovery of the mineral by someone who was certainly no geologist. A miller named John Ball, of Burwell, owned land just outside the town, on the Fenland edge. How exactly he came across the coprolites will never be known. He may have discovered that his turnips were growing with extraordinary liveliness and dug the earth up to see what was underneath. But what is certain is that in 1851 he discovered the hard rounded fossils which, at that spot, would only have been a few feet below ground, in the Greensand. He dug out a quantity and according to Lucas (1931), a fenland doctor who had heard the story by word of mouth, washed the clay off them and ground them to a powder in his windmill. He then treated the powder with an acid to make a fertiliser. This process was probably similar to that used for processing bones and dried blood for manure and this explains his seemingly broad scientific knowledge.

Apart from Ball's activities, there is very little evidence of anyone mining coprolite until the end of the 1850's. There are two main reasons for this. Firstly, in such a widespread and traditional industry as agriculture, practices always take a long time to catch a hold; in the same way, crop rotation spread extremely slowly. Ball probably found sales difficult enough, even though he was the only producer in the field. Added to the difficulties of opening a market, there were transportation problems; the railway network was still limited and river tolls still high. The second important factor was the public's lack of accurate geological knowledge that was so important with thin seams of mineral. Even university geologists had little experience in the complexities of the Gault and Chalk Marl, let alone the average landowner or tenant farmer. It seems that, up to 1860, most coprolite was only discovered accidentally.

The Growth of the Industry

The first recorded discovery of a coprolite bed after 1851 was at Cambridge in 1858 on Coldham's Common, probably where a pit was being dug for brickmaking. Practically all pits to the south were opened in the years 1858-70 and until 1872 there were no pits to the north of Cambridge except at Swaffham and Burwell. This is not to say that production was always higher in the former group;