VENUSJ2is around 1/200 of that of Earth (+/1 40%) - hence the comments about the small tidal bulge and the small tidal effect from the Sun mentioned about. The surface consists of 65% plains, 8% highlands and 27% lowlands. Tds and 27% lowlands. The largest mountain is Maxwell Monte, which is 12 km high. There is some evidence of plate tectonics, with Western Aphrodite Terra being the site of some crustal spreading (several cm per year). Other regions show deformation due to compression and convergence. However it is fairly certain that continental drift as the Earth knows it is unknown. The surface has been mapped in sub-kilometer detail by radar on an orbiting satellite (Magellan) (necessary of course because the surface is otherwise shrouded in clouds). The surface seems close to isostatic equilibrium, so maybe there is a fairly thin lithosphere/asthenosphere. There are some constraints on surface chemistry from the atmosphere, though this is a complex subject - see Lewis pp 459-462. A little is known of the surface rocks
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