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Summary

An extant regular field system dating from the Middle Iron Age

Protected Status: None recorded

Other Statuses/Codes: none recorded

Monument Type(s):

• FIELD SYSTEM (Middle Iron Age - 400 BC to 101 BC) + Sci.Date

Full description

An extant regular field system dating from the Middle Iron Age. Located and planned at 1:1250 by CCRA/National Trust in 1982 (1).

Optical Stimulated Luminescence (OSL) dating was carried out on three samples from this field system.

Site 3 was investigated in the most detail. A narrow trench was excavated through the boundary to expose and sample the entire stratigraphic sequence. This lynchet is one of several curving primary lines that delimit boundaries in the regular field system (2: Figure 8). These fields were dated relatively by their association with a small hamlet of stone-built Iron Age roundhouses, later transformed into Romano-British courtyard houses, which are located along the lynchet to the west of the sampling site. The earthwork seems to have acted as a field boundary since its construction, as it forms a prominent feature in the present landscape, with a drop of approximately 1.75m between the dry-stone wall on top and the ground surface downhill to the north. The excavated section revealed a feature with large granite boulders at its centre, which were interpreted as the remains of a stony bank (2: contexts 24 and 26 on Figures 5–6).

To provide detailed insights into the lynchet's construction and diachronic development, a total of 40 profiling samples and six dating samples were collected from across the earthwork. The West Penwith Survey (3) suggested that the Bosigran lynchets would already have been quite substantial by c. AD 500, as it was assumed that they had been accumulating eroded soil on their southern (uphill) sides for almost 1500 years (3: 88).

The OSL-PD, however, suggests that the stony bank at the core of the lynchet was constructed in the Middle Iron Age by cutting down into older Bronze Age soils (after c. 1320±160 BC (CERSA 300)) and underlying rab (2: Figure 6). This boundary appears to have remained fairly low until early medieval times, when the top and sides of the stony bank were progressively augmented by repeated additions of soil and smaller stones. This suggests that the landscape was exploited in much the same way from the Middle Iron Age until the Early Middle Ages (c. AD 590±70 (CERSA 289)), when management practices appear to have changed. This is notable because it probably coincides with the abandonment of the adjacent courtyard house settlement and the foundation of the new hamlet of Bosigran.

The profiling data show that the process of earthwork enlargement continued throughout this period, and on into the Late Middle Ages and post-medieval periods, resulting in the substantial earthen bank that now stands on the lynchet. During the later Middle Ages, a new stone facing was added to the lynchet's northern side, and in the post-medieval period, a dry-stone wall of granite boulders was built along the top of the bank. On the southern side, the gradual accumulation of soil against the developing bank from the Early Middle Ages to the present day accounts for no more than 0.40m of the sediment stratigraphy. Figure 6 illustrates this developmental sequence (2).

<1> Cornwall Archaeological Unit, Field Drawing (GRE) (Cartographic materials). SCO5089.

<2> Vervust, S., Kinnaird, T., Herring, P. & Turner, S., 2020, Optically stimulated luminescence profiling and dating of earthworks: the creation and development of prehistoric field boundaries at Bosigran, Cornwall, 2, 3 and 4 (Article in Serial). SCO29324.

<3> Herring et al, 2016, Archaeology and Landscape at the Lands End, Cornwall - The West Penwith Surveys 1980-2010 (Bibliographic reference). SCO29333.

Sources / Further Reading

Associated Finds: none recorded

Associated Events

• ECO5868 - Optically stimulated luminescence profiling and dating of earthworks: the creation and development of prehistoric field boundaries at Bosigran

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