02429nam a2200361 a 450000100080000000500110000800800410001910000170006024500680007726000510014530000100019650000160020652015520022265000130177465000190178765000150180665000090182165000190183065000100184965000100185965000220186965000110189165000090190265000140191165300110192565300130193665300330194965300140198265300360199665300100203265300140204265300110205615598902000-05-22       1980    bl uuuu  m   00u1 u    #d1 aMONIZ, A. C.  aFormation of an oxisol-ultisol transition in Sao Paulo, Brazil.  aRaleigh: North Carolina State Universityc1980  a290p.  aPhD.Thesis.  aThis study of an Oxisol-Ultisol transition allowed the development of a double-water flow model as the most important single factor in explaining the formation of soil structure as well as controlling the chemical and mineralogical transformation that occur during the soil development. According to this view, soil development results from the   action of both lateral - and base-water flow, integrated in the landscape, rather than the classic vertical interpretation of soil development. The argillic horizon is formed inside a layer having a blocky structure which runs along the sloping portions of both the   Itatiba and Mogi Guacu toposequences and thickens gradually downslope. This blocky structured layer is affected mainly by the lateral-water flow and its soil structure is formed by wetting and drying cycles. This layer, with higher bulk density than the oxic material underlying it, is interpreted to be compressed or consolidated by desiccation, according to soil mechanics terminology. The formation of a blocky structure from a fine granular structure represents the first step in the compression process. Prismatic and columnar structures are formed as the compression progresses toward the shrinkage limit of a particular texture. Further modifications in the structure result in the    formation of a sepic plasmic fabric where soil materials have crystalline swelling. Clay arrangement, starting at the ped surface when compression is low, extends inside the ped when compression is increased. The main feature of the........  aAcrisols  aclassification  aFerralsols  asoil  asoil structure  awater  aÁgua  aEstrutura do Solo  aOxisol  aSolo  aUltissolo  aBrasil  aFormacao  aMineralogical transformation  aSao Paulo  aSoil chemicophysical properties  aSolos  aStructure  aUtisol