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Eryri in the Late Bronze Age and Iron Age

Until recently, the presence of hill forts was thought to belong to the few centuries before Roman control. The forts were believed to be new developments designed to be a defence against the use of iron made weapons. However, due to the use of radiocarbon dating, many ideas and assumptions have now had to be radically altered. It is fairly certain now, that the earliest hill forts predate the Iron Age, by several centuries.

Of all the prehistoric remains in Wales, these are some of the most impressive, and undoubtedly the largest of all. Why were such massive defences needed? It is probable that these were due to the changes in climate that occurred in the centuries after around 1500 BC In this period, the average temperatures fell by about 2C. This change brought in what is known as the Sub-Atlantic climate period, a period that has lasted up to this day. The change in average temperatures led to a shorter growing season, especially in high latitude areas such as Britain. It is also likely that heavier rainfall occurred as a result, which in turn probably brought increased the amount of flooding in the lowland.

The marshes expanded in flat areas, peat began to grow and spread downhill: human communities were faced with a reduction in the amount of available agricultural land. In such a state of affairs, the territorial affirmation and defence of land from capture, would have been of prime importance for each tribal group or community. Not only does the presence of hill forts indicate the need for defence, it also shows that societies were led and that there were people with the power to induce others to take part in what would have been demanding and backbreaking work with little immediate benefit to the individual.

Dinas Dinorwig (O.S. 549 653) is indeed an impressive site once the full scale of the fort is realised. Much easier to see and comprehend is the magnificent Tre'r Ceiri, capping the southernmost summit of Yr Eifl (The Rivals) on the Lleyn peninsula above the village of Llanaelhaearn.

Not all the hill forts were huge structures; smaller hill forts and cliff-edge forts were usually fairly simple structures. They tended to consist of some form of an outer dyke and a ditch; a palisade of some form would have topped the dyke.



The stones forming the base of the dykes of Dinas Ty Du (O.S. 566 598) above Llanberis and Caer Carreg Fran (O.S. 547 627) can still be seen. Other artefacts from this period include some enamelled bronze found at Pen Y Pass (O.S. 6455)

Apart from the building of the large hill forts, the most dramatic change that took place at this time was the clearing of the woodlands on the valley floors. The uplands had been cleared in previous periods; however, the clearance of the lowlands was not for pasturage but for the establishment of fields and arable systems of farming. The story of Culwch ac Olwen; recorded in the Mediaeval collection Y Mabinogion, shows a folk memory of the clearances taking place during the final period of pre-history.

Many of the small stone field systems and old farms found in Northern Eryri date from this period. Some of these fields seem minute to us: however, they reflect the ploughing methods of the time. The implement used was not a plough in today's use of the word; it hardly turned over the soil. This lightweight ard was used to break up the upper section of soil, as it ripped through roots and vegetation. In some areas, the small fields represent the amount of land that the ard could plough in one day. The expansion of farmland and farmsteads continued into the period of Roman occupation.