Venus is probably similar to the Earth in that recycling of basaltic crust has been induced by the development of cratons: combinations of siliceous crust with high Mg:Fe mantle. Venus has less remaining energy sources at depth, but still enough to support the great plateaus, and to deliver appreciable heat close to the surface by convection. The main differences of Venus from the Earth arise from its lack of water, rather than higher temperatures. Lack of water (plus lower stress levels due to lesser energy) makes the upper mantle more viscous, and hence Venus tectonics more driven by bulk mantle, rather than boundary layer, characteristics. Making tectonics difficult to infer from Magellan imagery will be shallower and more widespread layers of weakness in crustal rocks obscuring the mantle-driven patterns. ¿ American Geophysical Union 1990