Venus

Processes affecting Venus include impact cratering, lava flows, solid-state creep (viscous flow of rocks at the surface due to high temperatures and pressures), and eolian (wind) effects. The latter include deflation (blowing away fine particles), wind erosion (forming yardangs), and wind deposition (formation of streaks, transverse dunes, and wind-shadow dunes). Weathering on the surface is due to interaction between carbon dioxide and sulfur dioxide at high temperature with silicate rocks. At elevations above about 2.2 mi (3.5 km) above mean planet radius, weathering seems to favor formation of iron-sulfur compounds and below that level, iron-oxide and calcium-sulfate compounds, tend to form. The latter was inferred from the nature of the reflected radar signal off surficial materials.