The Tupanciretã Formation, in Rio Grande do Sul, is constituted by a basal conglomerate that occurs only at the southern end of the area, by sandstones, siltstones and clays. The predominant lithologies are fine to very fine sandstones, often sandstones. Its granulometry presents the mean diameter of 2 to 4 ∅, standard deviation ranging from 1.0 to 2.0, sometimes from 2.0 to 4.0, and, therefore, poorly to poorly classified. The asymmetry is positive and the lepto to mesocurtic distribution. The grains of the sandstones show high sphericity, between 0.8 and 0.9, sub-rounding, about 0.6, polished surface texture.
