The chronology and long term dynamics of a low energy river system: the Kelvin Valley, central Scotland

Abstract

The long term (Holocene) channel and floodplain dynamics of a low gradient, low energy, fine grained aggradational fluvial system within a formerly glaciated landscape in central Scotland, the Kelvin Valley, are described from a series of sediment stratigraphic transects and 12 14C assays in a headwater reach between Kirkintilloch and Kilsyth. The 14C assays and dated archaeological sites on the floodplain together suggest that the River Kelvin ceased to aggrade more than 2000 years ago, probably much more, so the 4–6 m of channel and floodplain deposits are almost entirely of early to mid-Holocene age. The Kelvin Valley is characterized,despite its low flow characteristics, by a highly variable floodplain architecture, in which some transects suggest long term channel stability and strong partitioning of floodplain sedimentation and others indicate high channel mobility. This variation makes the application of general models of fluvial evolution difficult

After the ice: Lateglacial and Holocene landforms and landscape evolution in Scotland

“…There is also evidence that periods of floodplain aggradation or incision may even be asynchronous within a single catchment (e.g. Tipping 1999;Tipping et al 1999), and that the Holocene history of lowland rivers differs from that of upland rivers (Tipping et al 2008).…”

“…The evidence relating late Holocene alluviation or incision to prehistoric land-use change (particularly woodland clearance) through coincidence of timing is suggestive but remains tantalizingly inconclusive. Tipping et al (2008) of the alluvial deposits of the River Kelvin between Kirkintilloch and Kilsyth suggests that the Holocene alluvial history of the comparatively low-energy river systems of the Midland Valley (Central Lowlands) differs markedly from that of their upland counterparts. Multiple cores retrieved from four transects across the River Kelvin floodplain revealed up to ~3.5 m of mainly fine-grained sediments, locally underlain by peat up to ~1.5 m thick.…”

“…In consequence, there is a marked asynchronicity between periods of floodplain aggradation and episodes of fan accumulation (e.g., Tipping & Halliday 1994; Ballantyne & Whittington 1999; Reid et al 2003; Foulds & Macklin 2006). There is also evidence that periods of floodplain aggradation or incision may even be asynchronous within a single catchment (e.g., Tipping 1999; Tipping et al 1999), and that the Holocene history of lowland rivers differs from that of upland rivers (Tipping et al 2008).…”

“…They also asserted that the YDS witnessed major renewed floodplain aggradation, contending that ''alluvial units of this period are common in both upland and lowland'' and that the early Holocene was dominated by floodplain incision, allowing preservation of YDS alluvial units and terrace fragments. The only dated evidence for floodplain aggradation in Scotland during the YDS comes from the Kelvin valley, where cores record floodplain deposits overlain by peat then an upper layer of (Holocene) floodplain deposits (Tipping et al 2008). The three oldest radiocarbon ages obtained for the base of the peat (11.7-11.4 cal 14 C ka, 11.6-11.3 cal 14 C ka and 11.2-10.8 cal 14 C ka) imply that the underlying alluvium is of YDS age, possibly indicating floodplain aggradation at that time.…”

“…A Roman fortification, the Antonine Wall, cuts across the present flood plain, implying that aggradation must have ceased by the time of its construction in AD 140. Tipping et al (2008) concluded that the uppermost 4-6 m of alluvial deposits accumulated during the early and middle Holocene, and that floodplain aggradation ceased at least 2000 years ago, and probably much earlier.…”