Discussion on facies analysis in the Lower Greensand using ground-penetrating radar

Abstract

J. Eyers writes: In his recent paper Bristow (1995) presents an excellent account of the use of the ground-penetrating radar in deducing large-scale sedimentary structures in sands. However, there are several inaccuracies and misleading statements in the paper and these are dealt with in the order they appear in the text. Tectonic influence on sedimentation. The statement that the tectonic influence proposed by Eyers (1991) is 'refuted by the most recent Geological Survey Memoir ( Shephard-Thorn et al. 1994 )’ is unfair. The author is not going to discuss the influences on sedimentation nor the sand units that are the subject of the Eyers paper. The proposal of a tectonic influence on sedimentation patterns within the Lower Greensand is thus dismissed as requiring no further investigation, even though the author does not propose an alternative model or discuss the issue. Tectonic influence has also been proposed by Ruffell & Wignall (1990). Bristow's paper describes a small and unrepresentative unit of the majority of the Lower Greensand, the 'Red Sands', a unit previously intepreted as channelized deposits (C. R. Bristow 1963 ; Shephard-Thorn et al. 1994 ; Eyers 1992 a , 1995a , Eyers and references within). Readers interested in this possible tectonic aspect may judge the evidence for themselves in Eyers (1992a, 1995 a ). Shenley Limestone. Contrary to the statement that the Shenley Limestone is not exposed at the present day, this horizon has been exposed at various quarries during the period of my research, 1988–1995, including the best sections at Reach Lane and Munday's Hill, both north