During their formation, impact craters on Venus larger than 11 km in diameter acquired parabolic features composed of air fall deposits that are radar-dark in Magellan synthetic aperture radar images. A model of the parabola planimetric shape and size (the latter being a function of crater diameter) was constructed from the data of Campbell et al. <1992>. Reconstructing model parabolas around all impact craters with D > 11 km in the regions of the Venera-Vega sites revealed that parabolas cover 80--90% of the surface. These regions are representative of the majority of the Venus surface in terms of general geology and impact crater abundance. This implies that a very significant part of the surface of Venus was covered at least once with parabola deposits, and thus it is logical to look for them in the TV panoramas of the Venus surface taken by the Venera landers. These panoramas show the presence of soil and layered rocks, with the rocks (shown by the data of several instruments) consisting of porous, mechanically weak material, implying an altered or sedimentary (in a broad sense, including volcanic tuffs and impact deposits) nature. We propose the hypothesis that (1) the layered rocks may be the partly lithified and then partially eroded parabola deposits, while (2) the soil may partly be unlithified crater deposits and partly a product of the degradation of layered rocks. If this hypothesis is correct, then the interpretations related to the provenance of the materials studied geochemically by the landers may need revision. In particular, it is very possible that deep-seated (>1--3 km) rocks (the lower units of the regional plains complex, rocks of the plains basement, and plutonic rocks) are a part (perhaps significant) of the material analyzed by the landers. The possible presence of this deeply derived material should also be taken into account in selecting landing sites for future missions to Venus.