The Gault and its Junction with the Woburn Sands in the Leighton Buzzard Area,Bedfordshire and Buckinghamshire

Sections in the Gault and of the Gault-Woburn Sands junction exposed in the Leighton Buzzard area of Bedfordshire are described. These give a much clearer picture of the ammonite zonal stratigraphy than hitherto. The depositional history of the Albian sediments is discussed. The relationship of the Shenley Limestone to the regularis nodule beds in the south of the area is demonstrated, together with the nature of the mixed regularis and kitchini nodule beds seen in the central area. Periods of erosion occurred in post-kitchini mammillatum Zone times, and after renewed sedimentation in the eodentatus Subzone. Overlying these beds are clays of spathi Subzone age which pass laterally into glauconitic marginal loams against a platform of Woburn Sands in the northern part of the area. Upon this platform occur knolls of bedded Silty Beds, capped by Shenley Limestone, against which sediments of high spathi, intermedius and niobe Subzones age thin. The base of the Upper Gault, of high cristatum Subzone age, rests non-sequentially upon an eroded surface of the Lower Gault. Clays of orbignyi Subzone age are overlain by a bed of phosphatic nodules representing the lower part of the varicosum Subzone, which in turn is overlain by thick clays which may in part be of varicosum and auritus Subzones age.