In October 2002, Otley Gull was surveyed with a view to designating it as a Suffolk RIGS. RIGS are Regionally Important Geological and Geomorphological Sites, identified as the most important places in the county for geology and geomorphology outside statutorily protected nature reserves and Sites of Special Scientific Interest (SSSI). The term “gull” has come to refer in Suffolk to a watercourse deeply scoured by force of water, and these small incised valley landforms, of which Otley is a fine example, are found in many parts of the county. The stream flowing through this gull is a tributary of the River Deben catchment and the proposed RIGS is a 350m stretch of the stream valley, from TM199545 to TM203546. It is incised into the underlying diamicton, locally known as Chalky Boulder Clay.
Three transects were surveyed across the valley, identifying breaks of slope by eye and using clinometer and tape for slope measurements. One transect was at the upstream end of the gull at 190545, one was in the middle at 201546 and one at the downstream end at 202546. The depth of the incision showed considerable uniformity, being close to 3.5m at all three locations. The width across the top increased downstream from 16m at 190545 to 24.5m at 202546. The valley sides of the gull were convex at the top, but with a steep slope leading straight down to the channel. The steepest valley-side slope units on either side of the stream exceeded 25º with a mean of 37º for all three transects. A sample of 50 pebbles from the bed load taken under the footbridge at 202546 produced sub-rounded chalk (66%) and flint (24%) with a mean size (maximum diameter) of 28mm. This is consistent with their origin in the Chalky Boulder Clay, which is exposed in the valley sides in places.
A variety of fluvial landforms are exhibited within the gull. The mean channel width measured in the three transects was 0.75m and there are several incised meanders about 10-15m across (amplitude 5-7.5m). There is a well-developed alluvial fan near the upstream end of the gull and the steep slopes in the diamicton show a number of slope failure features. At the downstream end of the gull there is a river terrace with a slope of only 2º.
This charming little wooded valley incised into the arable fields of the boulder clay country makes a delightful interlude in the walk along the footpath from Otley to Ashbocking. The gull is easily viewed from the public footpath which runs along the right bank and across a well-maintained footbridge at 202546. I wish to thank Mr and Mrs A Kemp and Mr J F Haag for permission to survey the gull.
Sunday 25 May - SUTTON AND RAMSHOLT
Field meeting to see London Clay, Coralline Crag and Red Crag.
Meet at Woodbridge Railway Station at 10.30 am; we shall be driving on from there. Bring packed lunch and stout footwear. This is a joint meeting with Essex Rock and Mineral Society.
Saturday 14 June - ORFORD AREA
Field meeting to see recently cleared SSSIs showing Coralline, Red and Chillesford Crags.
Meet at Woodbridge Railway Station at 10.00 am; we shall be driving on from there. Bring packed lunch and stout footwear.
Sunday 6 July - WESTLETON BEDS
Field meeting to see Westleton Gravels.
Meet at Dunwich beach car park at 10.30 am. Bring stout footwear. Either bring packed lunch or join others of the party at the beach car park fish and chips café.
Wednesday 20 August - GIPPING VALLEY
Filed meeting to sites in the Gipping Valley (Chalk, Till and Gravels).
Meet at Bramford picnic site (TM128463), near the railway bridge, at 10.30 am; we shall be driving on from there. Bring packed lunch and stout footwear (it may be very muddy!)
Saturday 23 August - BULCAMP
Field meeting to see Norwich Crag at Bulcamp.
Meet at the entrance track to Union Farm on the B1123 road (TM443765) at 11.00 am. Bring packed lunch and stout footwear. This is a joint meeting with the Geological Society of Norfolk.
Details of the following events will be in the next White Admiral:
Saturday 6 September – Lark Valley
Saturday27/Sunday 28 September – Newmarket Rock & Gem Show (commercial event)
Saturday 18 October- Otley and Debenham
We stopped supplying zip files of the magazine for download, with issue 53.
This is because the service was very infrequently used and it saves space on the server.
If you miss downloading however please e-mail me, Adrian Chalkley
I will decide whether there is sufficient demand for an alternative method.