| Venus is an Earth-sized planet with no
evidence of Earth-like plate tectonics. At least 85% of the surface is covered
with volcanic flows, the remainder by highly deformed mountain belts. Even
with the high surface temperature (475°C) and high atmospheric pressure
(92 bars), the complete lack of water makes erosion a negligibly slow process,
and surface features can persist for hundreds of millions of years. Some
surface modification in the form of wind streaks was observed. Over 80%
of Venus lies within 1 km of the mean radius of 6051.84 km. |
|
The mean surface age is estimated to be
about 500Ma. A major unanswered question concerns whether the entire surface
was covered in a series of large events 500 My ago, or if it has been covered
slowly over time. The gravity field of Venus is highly correlated with the
surface topography, which indicates the mechanism of topographic support
is unlike the Earth, and may be controlled by processes deep in the interior.
Details of the global tectonics on Venus are still unresolved. |
|
