Home Counties North Regional Group FULL-DAY GEOLOGY FIELD TRIP Sunday 20 September 2015, 10.00 – 17.30 approx Geology and hydrology of the dip slope of the south of Kensworth, Bedfordshire, to Redbournbury, , (including Kensworth Lynch, Cell, and ) and building stones of Norman churches, and Iron Age and Roman archaeology. Led by John Wong FGS Meet at 10 a.m. at the Redbourn Common public car parking area off Hemel Hempstead Road (on some maps it is named The Common), opposite Old School Cottages in Redbourn village, post code AL3 7NG, grid reference TL103119. If you require a lift or can offer a lift please let us know. The surface geology in this area is mainly Lewes Nodular Chalk and Holywell Nodular Chalk capped by free draining clay-with-flints of variable depths on the hill tops; superficial deposits include periglacial brick earth, fluvio-glacial gravels, river gravels and alluvium. The local topography is characterised by the northwest-southeast trending undulating ribbon ridges and inter-fingering elongate dry valleys. We will see the River Red (and its source), which is a main tributary of the River Ver; the River Red is a reedbourne from which whence Redbourn derives its name. Since the River Red catchment area has none of its water abstracted, it keeps the River Ver flowing from its confluence southwards; whilst to the north of Redbourn village, the channel of the River Ver is a winterbourne flowing only after heavy rainfall or thawing of snow. John will explain the impact of construction of the M1 motorway on the River Ver and its tributaries and increasing seasonal flooding in the vicinity St Mary’s Church in Redbourn village celebrated its 900th anniversary in 2010; an interesting stop to see the weathering of the building stones, then we go to see the remaining of an Iron Age plateau fort the size of a football pitch outside Redbourn village. We have a toilet stop on High Street at the centre of Redbourn village; this is on a section of the Roman Watling Street and it has more public houses than any other High Streets of the same length in the U.K. In 2008, archaeologists from the Channel 4’s Time Team dug over the site in Friars Wash to the north of Flamstead village, the site being interpreted as a Roman temple site and declared to be of national importance. John will lead you to travel on the original Roman Watling Street which runs parallel to the A5. The next stop is lunch in a public house east of Kensworth Lynch village. After lunch, we will follow the winterbourne section of the River Ver to Kensworth Lynch village and Church End. We then travel back south and stop at Markyate Cell to see a small dry valley and John will tell you a haunting local legend, then travel to Flamstead village at 480 feet above the sea level. Since the nearby Friars Wash Pumping Station was opened in 1956, it has resulted in 2/3 of the River Ver being almost permanently dry, and the upper stretch of the River Ver from Kensworth Lynch village to Flamstead village is classed as a bourne. We will see a large dry valley in the southwest of Flamstead village. The 12th century St Leonard’s Church in Flamstead village has many medieval wall paintings among the internal Norman architectures, as well a variety of non-local building stones. John will discuss with you how the medieval farming field patterns could reflect the topography and also indicate changes in the underlying geology of the Flamstead village area. The next stop is a tour of the Redbourn Village Museum, admission free; then we travel to Redbournbury working watermill to see the millstones, where we can purchase freshly made bread and local ice cream, and to see some periglacial landforms nearby before travelling home in daylight. There is a maximum of 15 participants for this field trip with priority given to Fellows, Candidate Fellows and Juniors of the Geological Society who are members of the Home Counties North Regional Group. You can bring a packed lunch. Please book your places on a first-come-first-served basis by e-mail to [email protected] Attendees will be asked to sign the usual indemnity form for field trip insurance purposes before the start of the walk.

For more information on the Home Counties North Regional Group visit the website http://www.geolsoc.org.uk/hcnrg