The discovery of six Bronze Age boats and an intact prehistoric riverside at Must Farm, Cambridgeshire, is a stunning find. It also provides a glimpse of the human struggle with a changing environment, as David Gibson, Mark Knight and Kerry Murrell from Cambridge Archaeological Unit (CAU) told Matthew Symonds.
The boats did not sink accidentally. Five of the six craft were deliberately scuttled, their backplates removed so that the waters of the River Nene could flood in. No longer watertight the vessels would have foundered quickly, slipping from sight before settling on the riverbed silts. But this was no mass sinking as part of a ceremonial spectacular in a sacred place. The boats were sunk individually, over the course of six centuries from 1300-700 BC, amongst the traps and weirs of a well-managed watercourse. Now 150m of the channel are being excavated by CAU in Must Farm quarry. While this stretch of river was probably unremarkable to the Bronze Age inhabitants who worked it, the forces shaping their way of life were anything but.
Around the dawn of the Bronze Age an environmental catastrophe engulfed the plains of south-eastern England. A managed landscape where cattle were herded, red deer foraged and oak trees grew was gradually inundated by rising water. Vast swathes of these plains, the Mesolithic hunting grounds of Doggerland, had been claimed by the North Sea thousands of years before. Now it was Cambridgeshire’s turn. As the ground saturated, peat began to form and the Fens were born. Dry-land species retreated as their landscape drowned. By the close of the Bronze Age the cattle, red deer and oak were gone; to be replaced by beavers, pelicans, otters and water voles in a new, wetland world. But one mammal proved more than a match for this changing environment: humans.
While the emergence of a Fenland habitat did not displace the human population, it encouraged a new way of life. Before the Middle Bronze Age, their archaeology is essentially that of any other prehistoric society in southern England. The pottery assemblages and Late Neolithic and Early Bronze Age monuments would be entirely at home in the Wessex chalklands. It was only after 1500 BC that everything changed. As the peat thickened, and the area became ever less penetrable on foot, features that were uniquely Fen began to appear. The famous Flag Fen causeways and platform dug by Francis Pryor (see CA 119) typify this. It is around the southern end of the Flag Fen basin – an area of marsh that formed around 1300 BC – that Must Farm quarry lies. The ongoing CAU excavations there are providing a vivid insight into how a changing environment moulded a new world.
The clay’s the thing
The humble brick is to thank for the spectacular Must Farm discoveries. Deep deposits of Lower Oxford clay here, lying 20 or 30m below ground, rank amongst the finest in the country. Until recently this clay was especially prized by the brick industry, as it is rich in decayed Jurassic sea life. This ignites when fired, creating a particularly solid product. Renowned as the ‘London brick’, it earned its name after being used to rebuild most of the East End following the Blitz. Yet today the extra pollution the clay generates has fallen foul of environmental measures. In its heyday 20 brickyards were producing the London brick; now only one remains: the Must Farm operation run by Hanson. Still churning out millions of bricks a week, its appetite for raw materials is steadily revealing a pristine prehistoric landscape.
This is fortunate, because existing site detection techniques are blindsided by the Fens. Lying at depths of 4 to 6m, the prehistoric layers could be seen as no more than a thin veneer of human activity crowning the pre-Fenland geology. Yet it is still sufficiently far down to be invisible to aerial photography, and out of reach of field walkers and metal detectorists. Even the gravel sought by aggregate quarries does not take them so deep, while the soft Fen sediments rule out the construction of housing estates and the opportunities for excavation they bring. The brickworks provide our only window into the prehistory.
It was the way layers formed as the Fens developed that created this depth of archaeology. Every year the previous surface in the Must Farm channel was blanketed by a fine layer of silt. In places delicate lenses of fallen autumn leaves still survive, banding the sediment like tree rings. Over centuries this produced a marked difference in height. The latest boat in the channel, dating to around 700 BC, lies 1.3m higher than the earliest, which was scuttled around 1300 BC. In the 1930s Grahame Clark described the fen deposits as a ‘delicate chronological scale’, because he realised that British prehistory had been separated out there and sorted into layers. After the radiocarbon revolution and advent of hard scientific dates for prehistory its potential was all but forgotten, but the CAU archaeologists are now making full use of the chronological control it provides.
Wind in the willows
The archaeology reveals that from around 1300 BC those living in the area became steadily more preoccupied with access. Building the Flag Fen causeways was one natural response to the growth of swamps. Rather than connecting previously inaccessible spots, these structures maintained access by replacing lost dry-land routes. Yet in some places manmade walkways were not needed, as natural causeways known as ‘roddons’ already penetrated the marsh.
‘Roddon’ is a Fenland term. It refers to a former tidal river channel that was gradually choked by sand and marine sediments. Once silted up, these created a far firmer surface than the peaty bog that developed around them. Today, roddon courses are easy to spot in the landscape, because in the 17th, 18th and 19th centuries they offered the only substrata stable enough to support farms. It was one of these, now demolished, that gave Must Farm quarry its name. Yet roddons were also valued by the Bronze Age population, as they provided a dry passage through the wetland.
Must Farm’s roddon was doubly useful, because as well as providing a natural causeway, a freshwater channel developed along it, cutting into the hard marine sediment. Running from Northamptonshire out towards March, before debouching into the sea, the result was a major navigable watercourse easily accessible on foot. Believed to be a former channel of the River Nene, prehistoric people enthusiastically exploited its potential.
This is an extract. The full article can be found in issue 263 of Current Archaeology, on sale now.