The Glamorgan-Gwent Archaeological Trust
Historic Environment Record

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Primary Reference Number (PRN) : 02791.0w
Trust : Glamorgan Gwent
Community : Glyncorrwg
Unitary authority : Neath Port Talbot
NGR : SS8942894894
Site Type (preferred type first) : Early Medieval Dyke
Status : Scheduled Monument

Summary :
The dyke runs almost straight for 192m WNW to ESE. On the N. end, the bank and ditch measure about upper 7.5m by about 1m high overall, but the earthwork decreases in size towards the S. There is no sign of stonework.

Description :
Clawdd Mawr, Bwlchgarw, the dyke runs almost straight for 192m WNW to ESE and is located roughly 15m above the floor of a narrow saddle running from Mynydd Caerau. The N. end lies at the head of a steep-sided natural gully, the S. on a steep slope. There is a gap were a track crosses it, but this appears recent. Near the N. end, the bank and ditch measure about upper 7.5m by about 1m high overall, but the earthwork steadily decrease in size towards the S. end, where it is now merely a shelf about 1.5m wide. There is no sign of stonework.
On the three first edition OS maps (1877; 1899; 1918), another track can be seen, crossing the dyke on the southern half. The current one dosesn't appear in them.

Clawdd Mawr is a long dyke (c200m) composed of a bank and traces of flanking ditches. The dyke, which is also known as Bwlchgarw, sits astride a low saddle on the 470m OD contour between the mountains of Y Wernfa to the northeast and Mynydd Caerau to the southwest. The overall width of the dyke is c7.5m and is composed of a stone revetted earthwork bank c1m in height and shallow (c0.2m) ditch to the southwest. The dyke has been shown to have been cut into the natural northeast facing slope with an additional ditch and the stone revetment situated on the northeast side (Crampton 1966, 381).
An investigation by Crampton (1966, 380-82) has shown the dyke to have been built just as the Ericaceae pollen had reached its maximum, the soil structure being a podzol over podzol, forming since the early-medieval period on a podzol that started forming in the Bronze Age. Based on this evidence, this particular dyke would then be appreciably earlier than the other three dykes Crampton investigated (Bwlch yr Afan 02265.0m, Ffos Toncenglau 02261.0m and Bedd Eiddil 02266.0m) (Lewis 2006).

Sources :
Crampton, C.B. , 1966 , An interpretation of the pollen and soils in Cross-ridge Dykes of Glamorgan
Lewis, R. , 2006 , Cross Ridge Dykes of Southeast Wales: Survey and Excavation ( © Glamorgan-Gwent Archaeological Trust (GGAT))
01/pm desc text/RCAHM//1976/Invent I 3/no808
02/Desc Text/Cadw/ Full Management Report/2005/ Copy in further information file
RCAHMW,1976, Invent I, part 3, no808, p.8, Cardiff.

Events :
E005433 : Cross Ridge Dykes of Southeast Wales (year : 2006)

Related PRNs : 94690

Compiled date : 13-08-1992

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