North Park Quarry – Brewer Street extension, Bletchingley

Magnetometer survey by D Lewis and M Roseveare of Tigergeo Limited detected evidence of known former field boundaries and previous agricultural use. Three areas of probable quarrying activity were noted although quantities of magnetically susceptible debris, probably imported as a result of farming practices, made identification of discrete features problematic. A ground penetrating radar survey, to help develop a basic ground model and to highlight areas with enhanced potential for buried palaeosols, recorded a dry valley, now filled with soil and corresponding to a slight surface depression, where such palaeosols might be present. Archaeological and geoarchaeological evaluation by L Cappon of AOC, with sondages excavated to investigate the character of the dry valley and also to investigate the possible presence of palaeosols, revealed a sparse scatter of post-medieval archaeological features. The earliest archaeological evidence comprised six flints; four recovered from the topsoil and two from post-medieval ditches. Broadly dated to the prehistoric period, none was diagnostic. The earliest feature was a posthole that produced a single sherd of medieval pottery. All other features were of post-medieval date, comprising field boundary ditches depicted on OS maps, previously unmapped ditches and a small number of minor parallel gullies, none of which were identified by the magnetometer survey. The fill of the dry valley was excavated at nine locations and revealed a sequence of scoured, braided watercourses, filled with sand and medium-sized gravel. Dense gravels at the base of the channel were overlain by layers of smaller, less dense gravel, indicative of a slower-moving fluvial environment, scouring less than initially. Some of the deposits had the appearance of cryoturbated material suggesting a late glacial date for the feature. An assessment of each trench was conducted for its potential for palaeoenvironmental study, and any evidence of old ground surfaces, buried soil horizons, laminated sediments or waterlogged deposits. The trenches were found to be largely sterile, containing predominantly a thin layer of pale yellow sand, overlain with a grey sandy clay and a grey/brown topsoil; typical of soils overlying the Folkestone formation. No peat, waterlogged deposits, laminated sediments or significant deposits were encountered.