Earth hummocks in West Dartmoor, SW England : characteristics, age and origin

Auteur(s) et Affiliation(s)



Description :
Extensive fields of vegetated, dome-shaped earth hummocks occur on slopes of up to 15° at elevations of 320–440 m asl on Dartmoor, but are limited to terrain underlain by metasedimentary rocks and dolerite, and absent from granite areas. Hummocks occur within archaeological sites, implying formation within the last 3000 years and ruling out development over permafrost. The hummocks are composed of frost-susceptible silty soil with occasional clasts, but exhibit no evidence for cryoturbation or diapirism. Hummock age, distribution and characteristics are incompatible with non-frost action origins. The AA. suggest that hummock growth may reflect migration of silt in advance of inclined freezing planes until equilibrium is achieved with soil loss down hummock sides. Their results confirm that hummock formation by frost action occurs on silty soils in humid cool temperate climates with only limited seasonal frost penetration.


Type de document :
Article de périodique

Source :
Permafrost and periglacial processes, issn : 1045-6740, 2012, vol. 23, n°. 2, p. 152-161, nombre de pages : 10, Références bibliographiques : 53 ref.

Date :
2012

Editeur :
Pays édition : Royaume-Uni, Chichester, Wiley