03.3 (40.87 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).
09.4 (1.13 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).
