Noncryogenic deformations in Loch Lomond Stadial to Early Flandrian coversands in North Lincolnshire, England

Abstract

In contrast to the Late Dryas Stadial aeolian coversands in the Netherlands, there are no frost structures in their approximately coeval counterparts in north Lincolnshire, England. Faunal evidence for cold conditions in the latter category can be reconciled with the absence of cryogenic deformations by assuming that the annual snow cover was thick enough to insulate the sands from frost action. This paper discusses two types of postdepositional deformations in the north Lincolnshire coversands to which, at first glance, a cryogenic origin might be attributed. It is shown, however, that nonperiglacial processes account more adequately for their presence in these deposits. Involutions associated with a hydromorphic paleosol are due to unequal loading and slow upward percolation of ground water when the sands that underlie the contorted layer were waterlogged during some period in the past. Fissures reminiscent of frost cracks, are interpreted as tension gashes produced by a slight updoming of the clayey or shaley substrate of the coversands in the proximity of cuesta scarp-faces.