10.15 (43.25 ha Index 131)
This group includes two associations of soils that, from a geomorphological and geographical point of view, are different, but which have been brought together because they are made up of soils with similar characteristics. A first association is located mainly in the Dpto.de Soriano, being important in the region southwest of Egana. To a lesser extent it also exists in the Department of Rio Negro and somewhat in the Department of Paysandu. The geological material corresponds to clayey sandy sediments and clayey silt, with abundant sand. The relief is gently undulating, with a predominance of slopes of 2 to 3%. The predominant soils are Typical and Luvic Subeutric Brunosols (medium and maximum Brown Grasslands), very dark brown to black in color, sandy clay loam to sandy loam texture, medium and high fertility and moderately well to imperfectly drained, and Luvic Ruptic Vertisols (Grumosoles). , very dark brown to black in color, clay loam texture, high fertility and moderately well to poorly drained. The second association referred to occurs on the transitional slopes between groups corresponding to the Fray Bentos formation located at higher altimetric levels and the Cretaceous groups, located at lower altimetric levels. Its greatest frequency occurs in the Department of Paysandu and, to a lesser extent, in the Departments. from Rio Negro and Soriano. The geological material is a colluvial sediment with a mixture of Fray Bentos and Cretaceous lithologies. The relief corresponds to slightly convex slopes, with slopes of around 2%. The dominant soils are Typical and Luvic Subeutric Brunosols (medium and maximum Brown Grasslands) similar to those already described in the previous association. The areas under crops and stubble predominate over the pastoral areas. The first association mentioned integrates the Cuchilla de Corralito unit of the chart at a scale of 1:1.000.000 (DSF), while the second is included mainly in the Young and Fray Bentos units of the same chart.
09.4 (10.59 ha Index 57)
This group is located in the Departments. of San Jose, Canelones y Colonia, being recognizable in the surroundings of Raigon station. The geological material includes sediments of very variable lithology, including mudstones (clayey silt) with gravel, clayey cement sandstones, arkose, clays, etc. belonging to the Raigon formation of the late Tertiary. The relief is made up of dissected slopes, with marked convexity and strong, short slopes of the order of 4 to 10% (rumps). The soils are very variable, although in general the presence of gravel remains constant. The predominant Luvic, sometimes Typical, Subeutric Brunosols and Typical Subeutric Argisols (Praderas Pardas maximas) should be mentioned. The upper horizons are brown to dark brown in color, loamy texture, sometimes silty loam with common gravel, medium fertility and somewhat imperfect drainage. In the Department of Colonia and south of Ecilda Paullier, the Argisols are sandier in texture. As accessories, a wide variety of soils related to lithologies of this formation have been determined in various places, such as Vertisols (Grumosols) of gray colors and Inceptisols (Regosols) formed from arkosic sediments. It should also be noted the presence of soils (normally Brunosols) whose upper horizons have developed from a silt-clayey sediment, corresponding to the accumulation of the overlying interfluve (Libertad formation) and the lower horizons of lithologies of the Raigon formation, with less proportion of silt and major fraction of clay, sand and gravel. The current use of the land is variable, depending on the location of the unit. It can be indicated, however, that in the south of the Dpto.de San Jose It has been under cultivation, currently experiencing severe erosion. This group, for reasons of scale, integrates the Kiyu unit in the Department of Colonia and part of San Jose, the Tala-Rodriguez unit in the Departments. of San Jose y Canelones and the Libertad unit in the Department of San Jose of the letter at a scale of 1:1.000.000 (DSF).
10.6a (7.35 ha Index 206)
This group is located as a discontinuous strip in the south of the Departments. of Canelones, Montevideo, San Jose y Colonia. The geological material corresponds to clayey silt sediments from the Quaternary, brown to orange-brown in color. The relief is gently undulating, with a predominance of slopes of 1 to 3%. In the Department of Canelones, approximately towards the east of Toledo, the relief is stronger since it is influenced by the proximity of the crystalline basement giving a predominance of slope of 2 to 4%. The predominant soils correspond to Subeutric Brunosols, sometimes Eutric, Typical and Luvic (medium and maximum Brown Grasslands) of brown to dark brown color, silty loam texture, high fertility and moderately well drained. The predominant use in the Departments. of Montevideo y Canelones It is horticultural-fruit and crops on a small farm scale. In San Jose y Colonia There are summer-winter crops, potatoes, etc. at the medium chakra level. This group makes up the Kiyu units (Colonia y San Jose) and Toledo (Montevideo y Canelones) of the chart at a scale of 1:1.000.000 (DSF)
03.3 (1.82 ha Index 96)
This group corresponds to the plains of rivers and streams that occur associated with hills of crystalline basement. An example is the existing plain in the Arroyo Santa Lucia Chico. The geological material corresponds to clayey silt sediments and, close to water courses, alluvial sediments of variable textures and stratified. They are rapid and short-duration flood plains, with meso-relief, showing channels and meanders, typical of their fluvial origin. The dominant soils correspond to Eutric Melanic Planosols, sometimes cumulic, very dark brown to black in color, silty loam and when cumulic, silty clay, very high fertility and imperfect drainage, and Gleysols, Typical Luvic, Melanic, black to black in color. very dark gray, silty clay loam or silty clay, very high fertility and poor drainage. The use is pastoral, with summer meadow vegetation and in the humid areas hydrophilic and uliginous communities are associated. In the riparian areas, with Heterotextural Fluvisols (Alluvial Soils), there is the typical river forest throughout the country. This group, for reasons of scale, is included in the San Gabriel - Guaycuru unit on the map at a scale of 1:1.000.000 (DSF).
