2]) forest SPINY FOREST- THICKET Alluvium 29 300 2 230 590 Dunes 9 900 220 1 660 Conglomerates 23 250 2 230 520 Limestone 17 690 2 270 1370 Sand 36 510 6 570 4 540 Sandstone 58 170 5 520 3 250 Duripan
& 850 0 390 duricrust Clay & marl 39 220 5 140 1 940 Subtotal 214 870 (36%) 24 180 14 260 sedimentary Non sedimentary 376 270 7 740 4 100 Total 591 140 31 920 18 360 Lithology Area ([km.
Moreau AMSDS, Costa LMD, Ker JC, Gomes FH (2006) Genesis of hardened horizons, fragipan and duripan in soils of the coastal tablelands of south Bahia.
duripans, fragipans and cohesive layers) often recorded in soils formed from the Barriers Group may have, in fact, a sedimentary origin rather than a pedogenetic one.
Older soils generally tend to be more complex and show more extensive duripan
(caliche) development and clayrich B-horizons (Othberg, 1994).
Aridisols will have one or more of the following features within 100 cm of the soil surface: a calcic, cambic, gypsic, natric, petrocalcic, petrogypsic, or a salic horizon, or a duripan or an argillic horizon.
Argids have an argillic or natric horizon, but not a duripan or a gypsic, petrocalcic, petrogypsic, or salic horizon.
3] Cambric (Bw, Bg) Nonilluvial physical or chemical change Duripan (Bqm) Hardpan cemented by silica Fragipan (Bx) Dense, brittle, loamy-textured pan Gypsic (By) Accumulation of gypsum Natric (Btn) Argillic horizon high in sodium Oxic (Bo) Highly weathered horizon with a mixture of Fe and Al oxides and silicate clays Petrocalcic (Ckm) Cemented calcic horizon Petrogypsic (Cym) Cemented gypsic horizon Salic (Bz) Spodic (Bh, Bs) Organic matter and Al and Fe oxide accumulation Sulfuric (Cj) Highly acidic with Jarosite mottles TABLE 3-3 Names of the soil orders in Soil Taxonomy and their major characteristics.
In addition, they have one or more of the following diagnostic horizons: argillic, natric, cambric, calcic, petrocalcic, gypsic or salic, or duripan
Tepetates are volcanic soils that consist of a duripan
exposed through erosion of the overlying soil.
(Chapter 3)--A relatively impermeable layer in soil composed of cemented silica.
In arid regions, they are often calcic, and the soils containing them are therefore classified as duripan
phases of calcisols.
Caliche and duripans
are layers of soil in which chemicals cement soil particles together.