Data/hora: 17/06/2024 01:48:54

Biblioteca(s): | Embrapa Solos.
Data corrente: | 22/11/2002
Data da última atualização: | 22/11/2002
Autoria: | BRYANT, R. B.
Título: | Physical processes of fragipan formation
Ano de publicação: | 1989
Fonte/Imprenta: | In: SMECK, N.E.; CIOLKOSZ, E.J. Fragipans: their occurrence, classificacao and genesis. Madison: Soil Science Society of America, 1989. (SSSA. Special Publication, 24).
Páginas: | p.141-150
Idioma: | Inglês
Conteúdo: | An understanding of the relationships between fragipans and their occurrence in landscapes appears to lie partially with an understanding of the physical processes of soil formation that result in high bulk density, close-packed arrangements of grains, and coarse prismatic structure. With respect to fragipans formed in glacial-till deposits, compaction by the weight of the glacial ice mass does not fully explain fragipan features nor was it the last physical process to act on extensive areas of till-derived sediments that presently have fragipan features. Micromorphological studies of fragipans provide little evidence in support of the hypothesis that physical characteristics of fragipans are the result of the process of alternating cycles of shrink/swell andinfilling of pores. The initial desiccation of a wet soil mass that occurs during the physical ripening process seems capable of producing the bulk density, close-packed arrangements of grains, and coarse prismatic structure associated with fragipans. Subsequent wetting and drying cycles probably cause little alteratiuon of soil structure and skeletal grain arrangement in subsurface horizons having low COLE values. The physical ripening process follows draining of a water-deposited sediment, deposition of a melt-out till deposit, congeliturbation, wet-mass colluviation, and melting of a permafrost. Self-weiht collapse of a wetted sediment and subsequent physical ripening is proposed as a physical process of fragipan formation in loess deposits in the lower...
Palavras-Chave: | Estados Unidos; Solos.
Thesaurus Nal: | fragipans.
Categoria do assunto: | --
Registro original: | Embrapa Solos (CNPS)
Exemplares: | CNPS - (1135-1) - ADC - PL - -- - 631.4 - S637f - 1993.00062 - DIS