True Resistivity of the Lower Sediments

The green color (>60 O-m) shows areas with deep and permeable sediments, while the yellow zones represent less favorable materials (30-60 O-m). Red and purple coloring (<30 O-m) marks the least permeable zones. An extensive green area can be seen in the right margin of the river near Carapongo, trending westwards, where the best aquifer conditions may be found at depth, and where wells may be drilled down to bedrock. Yellow areas (30-60 O-m) may be interpreted as marginal in importance and they should only be used for water wells after drilling in the green areas is completed. There is an extensive unfavorable "purple" area, corresponding to the Santa Anita town, which can be explained by the presence of clays; this has been confirmed by drilling and our well-logs.

Bedrock Topography

Basement morphology of impermeable rock is shown as contour levels, which present an area of great bedrock depth, colored in dark blue, with more than 200 meters; this shows the position of probable paleochannels with an approximate layout of the deep valley axis. The edge of the survey grid, shown with pink coloring, marks depth 0 meters to bedrock, except in areas with no geophysical information is available. An error of some 20%, inherent to these Resistivity computations, may be expected.