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Quaternary sediments of pampean plains, particularly in Buenos Aires province, south of Córdoba and La Pampa, frequently had sandy beds at the sequency top. They had named with differents formational names, and were considerated of mammal age Lujanense (upper Pleistocene), in some cases with his upper beds in Holocene. In center La Pampa province, there are: great sandy beds named Meauco Formation, which have physical continuity with similar deposits within Buenos Aires province to the east. In this work four sedimentary detailed profiles near Jagüel del Monte are described and interpretated. From this is evident that two wets periods take place with a poor or nule sedimentation rate, and paleosoils development, so during time period in which Meauco Formation was deposited, five stages with different climatic environmental conditions take place: dry - wet - dry - wet and dry. [ABSTRACT FROM AUTHOR]

This paper consists in the hydrogeological study of a region of about 20.000 Km2 in the middle west of the province of La Pampa in the Argentine Republic, between parallels 36° and 37° 45', S latitude, and meridians 66° and 67° 30' W (approximately the "Atuel" river cliffs). Cattle breeding is the major activity of the region, limited by water availability. The region is crossed diagonally by the "Chadileuvú or Salado" river and its affluent "La Barda" stream. The water regime of both rivers is determined by consumption in the upper parts of the basin that turned, with the passing of years, from an original simple snow regime into an antropic one. Their water volume and salt content are variable. Both streams are of effluent nature, except for La Barda, which sometimes presents a reverse regime. The weather of the region is dry; its mean rainfall is about 350 mm/year. Approximately 50% of its surface is covered by eolic sand, without soil profile, and therefore it has a low retention capacity. In that way, effective infiltration is possible. It has been inferred, from standardized water balances containing available climatic information, that when rainfall is near the historical average, recharge is negligible, but it is significant when rain is over. To this direct recharge, indirect recharge is added in some areas, generated by runoff from outcrops of hydrological basement, as much as, from the high slopes in the far west of the region. Regarding underground water resources, the probable presence of deep confined aquifers is analyzed first, and then, in particular, that of the phreatic ones. Chemical composition presents a wide range of variability, derived from the different formations on which they are contained. On the other hand, it is very interesting to notice, the close correlation between geomorphologic environment and chemical nature of phreatic waters, what together with the flow pattern, makes it possible to determine five hidrogeological environments with common characteristics. [ABSTRACT FROM AUTHOR]