Geology of Sheets SY 99 NE and SE and parts of SY 99 NW and SW Corfe Mullen - Lytchett Minster, Dorset: part of 1:50 000 sheet 329 (Bournemouth)

Some 55 km² of the Corfe Mullen - Lytchett Minster area have been geologically surveyed at the 1:10,000 scale. As a result, the detailed stratigraphical sequence established in the Poole Formation during 1984 has been followed westwards; additionally, sand members within the London Clay have been recognized and mapped over a wide area. Gentle E-W flexures which are superimposed on the regional dip of l° SE, probably overlie faults of pre-Aptian age (mid-Cretaceous). Dinoflagellate floras collected from the clays of the Poole Formation and London Clay allow the various stratal units to be placed within the known dinoflagellate zonal sequence. Landslips developed on the clays of the Reading Formation, and solution-collapse hollows developed over the Chalk have been identified at a number of sites. Many of the clays of the London Clay and Poole Formation have been exploited for bricks, tiles and pottery, but most pits are now disused and mostly backfilled. In addition, extensive reclamation of low-lying ground and tidal flats has occurred. A map showing the extent and nature of the Made Ground is included. Summaries of grading data for sand samples collected in the field are presented graphically. River Terrace Deposits occur at various levels; except in the extreme south and north they have been either built over, or exploited, or are of too limited extent or thickness to form significant resources. An account of the hydrogeology of the district is included. The application of geophysical techniques, principally using the EM 31 and 34 to measure ground conductivity as an aid to geological mapping, is discussed in Appendix 1. A glossary of technical terms appears at the end of the report.