Two superposed diamictites in the middle part of the Itararé Subgroup, cropping out along highway SP-280 in central-eastern São Paulo State, are separated by a boulder pavement associated with a disconformity at the top of the lower diamictite. Wedge-shaped bodies up to 3 meters in height made up of sandstone, conglomeratic sandstone, and admixed sandstone and diamictite, taper downwards from the disconformity into the lower diamictite. Other channel-like bodies of sandstone occur at the top of or enveloped by the lower diamictite. The former of these structures are interpreted as possible pseudomorphs or casts of ancient ice-wedges developed in frozen ground during the Gondwana glaciation. The latter probably include subglacial and surface channels eroded and filled by fluvio-glacial streams. These features suggest the occurrence of a rigorous periglacial climate in this part of the Paraná Basin during the Late Paleozoic.
