Middle Pleistocene till lithostratigraphy in south Bedfordshire and the Hitchin Gap
A revised lithostratigraphy and glacial history of north Hertfordshire and south Bedfordshire is based upon detailed textural data in the clay to fine gravel fraction, carbonate content, small clast lithological data and macrofabrics, derived from laboratory and field analyses of tills from 30 sites. These include four deep boreholes sunk within the Hitchin Gap. A range of statistical procedures was used, including multivariate analysis of the petrographic properties, enabling the identification of tills from two separate incursions into the Gap. A further till-type was identified in south Bedfordshire indicating an ice advance from the northwest/NNW extending at least as far east as Milton Bryan. Statistical comparison with tills in the neighbouring Vale of St. Albans suggested the presence of the Ware Member till within the Gap. Two hypotheses are suggested to explain variations in lithological content of tills north of the Chalk scarp. The first envisages ice entering the study area along the different trajectories suggested by Fish and Whiteman (2001). During the early part of the glaciation, ice reaching the west of the study area would approach from the north, crossing a shorter distance over Chalk bedrock
Brownsell, Wendy Joan
Pleistocene ; Anglian ; Bedfordshire ; Hertfordshire ; Hitchin Gap ; Till ; Palaeoenvironment ; Palaeogeography
Middle Pleistocene till lithostratigraphy in south Bedfordshire and the Hitchin Gap. A revised lithostratigraphy and glacial history of north Hertfordshire and south Bedfordshire is based upon detailed textural data in the clay to fine gravel fraction, carbonate content, small clast lithological data and macrofabrics, derived from laboratory and field analyses of tills from 30 sites. These include four deep boreholes sunk within the Hitchin Gap. A range of statistical procedures was used, including multivariate analysis of the petrographic properties, enabling the identification of tills from two separate incursions into the Gap. A further till-type was identified in south Bedfordshire indicating an ice advance from the northwest/NNW extending at least as far east as Milton Bryan. Statistical comparison with tills in the neighbouring Vale of St. Albans suggested the presence of the Ware Member till within the Gap. Two hypotheses are suggested to explain variations in lithological content of tills north of the Chalk scarp. The first envisages ice entering the study area along the different trajectories suggested by Fish and Whiteman (2001). During the early part of the glaciation, ice reaching the west of the study area would approach from the north, crossing a shorter distance over Chalk bedrock
middle_pleistocene till south gap revise glacial history north hertfordshire south base_upon detailed data clay fine fraction carbonate content small data derive laboratory field analyse till site include deep boreholes within gap range statistical procedure use include multivariate_analysis petrographic property enable identification till two_separate incursion gap till type identified south indicate ice advance northwest extend least far_east statistical comparison till neighbour suggest presence ware member till within gap hypothesis suggest explain variation content till north chalk first envisage ice enter study_area along different trajectory suggest fish early_part ice reach west study_area would north cross short distance chalk bedrock