Gases remain trapped longer in the magma, and then are released explosively. Coronae form a distinctive class of large volanoes on Venus. They are characterized by large, concentric rings of fractures, ridges, and troughs. Evidence of upwelling of hot material, fracturing of the crust, and then collapse. Pancake domes are thought of form in a similar way.
Wrinkle ridges are most common feature on the plains.
The thick atmosphere is very sluggish at the surface. Venus has evidence of landslides. Venus has no plate subduction. Surface recycling occurs vertically, with mantle upwellings triggering volcanism and mantle downwellings resulting in compression. Regions that are bright in the reconstructed radar images have higher radar reflectivity.