The effect of the bedrock through the erodibility of the soils and their high arable potential is a marked contrast with the Arrow valley draining low mountains directly to the west. This catchment on Palaeozoic bedrock has four Holocene terraces produced by a dynamic channel sensitive to climatic shifts (Macklin et al., 2003) and no over-thickened anthropogenic unit.

The Culm Valley drains the Blackdown Hills which are a cuesta with a plateau at 200–250 m asl. and steep narrow valleys with strong spring-lines. The stratigraphy of the Culm Valley also shows a major discontinuity between lower gravels, sands, silty clays and palaochannel fills, and an upper weakly laminated silty-sand unit PF01367338 (Fig. 7). However, this upper unit is far less thick varying from under 1 m to 2.5 m at its maximum in the most downstream study reach (Fig. 5). For most of the valley length it is also of relatively constant thickness PLX3397 solubility dmso and uniform in grain size

and with variable sub-horizontal silt-sand laminations blanketing the floodplain and filling many of the palaeochannels. The planform of the entire valley is dominated by multiple channels bifurcating and re-joining at nodes and conforming to an anastomosing or anabranching channel pattern, often associated in Europe with forested floodplains (Gradziński et al., 2000). Again organic sediments could only be obtained from the palaeochannels providing a terminus post quem for the change in sedimentation style. These dates

are given in Table 2 and show that the dates CYTH4 range over nearly 3000 years from c. 1600 BCE to 1400 ACE and that the upper surficial unit was deposited after 800–1400 ACE. In order to date the overbank unit 31 OSL age estimates were made from 22 different locations. The distribution of these dates is consistent with the radiocarbon dates providing an age distribution which takes off at 500–400 BP (c. 1500–1600 ACE) in the High Mediaeval to late Mediaeval period. This period saw an intensification of farming in the Blackdown Hills and although the plateau had been cleared and cultivated in the Bronze Age pollen evidence suggests that hillside woodland and pastoral lower slopes persisted through the Roman period ( Brown et al., in press), as summarised in Fig. 7 and Table 3. This intensification is associated nationally with the establishment and growth or large ecclesiastical estates which in this catchment is represented by the establishment of a Cistercian abbey at Dunkerswell (est. 1201 ACE), an Augustinian abbey at Westleigh, an abbey at Culumbjohn and a nunnery at Canonsleigh. In the religious revival of the 12th and 13th centuries ACE the Church expanded and increased agricultural production as well as its influence over the landscape ( Rippon, 2012).