CURRENT-BEDDING DIRECTIONS IN SANDSTONES OF LOWER RET1CULOCERAS AGE IN THE MILLSTONE GRIT OF WHARFEDALE, YORKSHIRE

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Abstract
Summary: A statistical study of foreset-bedding within a limited area of R 1 sandstones in the Millstone Grit shows that current bedding dip directions exhibit a much greater angular range than has previously been supposed. These varying dips are interpreted as the foreset beds of two small delta cones on the surface of the main Millstone Grit delta. They are to be compared with similar cones now forming on the surface of the Colorado delta. From this interpretation it is deduced that the immediate source, but not necessarily the ultimate source, lay towards the north and east. Thus Gilligan’s conclusion that the Millstone Grit detritus was transported from the north-east is confirmed. Investigation of the long axis orientation of sand grains and the c-axis orientation of quartz grains in a fine R 1 stage sandstone shows that a preferred optical and dimensional orientation is present. However, this method is not considered to be practical for large-scale palaeogeographical interpretation because a great number of observations are required even to establish flow directions over a few square inches. Thus it is concluded that some other technique is required for directional studies of these fine sandstones.

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