The Lincolnshire Wolds are a range of low hills in the county of Lincolnshire, England which run roughly parallel with the North Sea coast, from the Humber Estuary in the north-west to the edge of the Lincolnshire Fens in the south-east. They are a designated Area of Outstanding Natural Beauty (AONB), and the highest area of land in eastern England between Yorkshire and Kent. Geology The Wolds are formed largely from a series of pure marine limestones formed during the Cretaceous period, known collectively as the Chalk Group. The chalk overlies a series of other sedimentary strata of late Jurassic/early Cretaceous age. The strata dip gently to the east and form a scarp which runs southeast from Barton upon Humber via Caistor before it loses its identity north of Spilsby. To the north of the Humber Gap, the same formations continue as the Yorkshire Wolds. The rock succession in stratigraphic order i.e. youngest/uppermost first, is this: White Chalk Subgroup Burnham Chalk formation Welton Chalk Formation Grey Chalk Subgroup Ferriby Chalk Formation Hunstanton Chalk Formation The thin Hunstanton Chalk and the Ferriby Chalk formations form much of the west facing Wolds scarp but it is the overlying Welton Chalk Formation which forms the greater part of the easterly dip-slopes with the Ferriby Chalk extensively exposed within the dry dip-slope valleys. The Burnham Chalk Formation forms an indistinct secondary scarp to the east of the main scarp between Barton and Louth. In the north between South Ferriby and Grasby, the lower part of the scarp is formed from the Kimmeridge Clay Formation. A series of other rock layers intervene from the Caistor area southwards, uppermost of which are the green-brown Carstones: Lower/early Cretaceous Carstone Formation (sandstone) Roach Formation (interbedded mudstone and limestone) (present from Stenigot southwards) Tealby Formation (mudstone - but including the 'Tealby Limestone Member') Claxby Ironstone Formation Upper/late Jurassic Spilsby Sandstone Formation Kimmeridge Clay Formation The numerous dry valleys cut into the dip-slope are typically floored by head, locally derived clay, silt, sand and gravel. The western valleys were created during recent glacial periods through the action of water over frozen ground whilst many in the east represent subglacial drainage. During the last ice age (Devensian), ice encroached upon the Wolds from the northeast and entered the Humber gap from the east but did not cover the Wolds, hence there is no Devensian age glacial till on these hills. However