The local geological memoir (Smart et al., 1966) reports the existence of river terraces along the Elham Valley but they are not obvious to me.
The first mention of a terrace in the memoir, which you would encounter on a journey downstream, is one around Lyminge which is described as a discontinuous bench at an elevation of “around 400ft” (122m AOD)
Neither of the linear features mentioned at the beginning of the section on The Elham Valley are convincing river terraces; they do not include a level platform which is a necessary requirement for remnant flood plain. If the 400ft terrace exists around Lyminge, it is elusive.
River terraces are normally formed in the downstream parts of valleys where the river has sufficient energy to cut down into the valley floor, leaving parts of the previous floor on the edges of the valleys in the form of terraces. It is difficult envisage how terraces could have formed in the absence of sizeable rivers. But the outline of Head deposits at the top of the Elham Valley (an indicator of low lying land) suggests that rivers once flowed north through the cols at the head of the valley (see section 2.3 in “Some Origins of Chalk Downland Landscape”). In which case, rivers of a sufficient size to form terraces could have been present.
Andrew Coleman
Rev. 12/08/2024
Reference:
Smart, J. G. O., Bisson, G., & Worssam, B. C. (1966). Geology of the Country around Canterbury and Folkestone. Her Majesty’s Stationery Office.
Geomusings 