7. Venus: The veiled planet
Fifteen percent of the Venus surface comprises highlands, where the largest volcanoes are found, concentrated on or near the equatorial highlands. Large-scale plumes of rising magma have probably pushed up this globe-circling, elevated region from below. When the molten rock pierced the surface, lava flowed out to form towering volcanoes that are perched atop the raised highlands. Some of the volcanoes are found in Beta Regio on the western side of the equatorial highlands. Several rise out of Atla Regio in the eastern end of Aphrodite Terra, including Maat Mons and Sapas Mons.
One of the highest volcanoes, Maat Mons, rises 9 thousand meters above the surface, and spreads 200 thousand meters across it. Sapas Mons is shorter and broader. Both peaks are known as shield volcanoes, because they have the shape of a shield or an inverted plate. Similar giant shield volcanoes are found in the Hawaiian Islands, each with a broad base and gentle slopes.
The region of Venus that most closely resembles terrestrial mountains is Ishtar Terra, located at far northern latitudes. It consists of an elevated plateau, Lakshmi Planum, which is bounded on three sides by mountain belts the Danu, Akna and Freya Montes. Lakshmi just drops off into the surrounding plains on the fourth side, forming an immense cliff. The belts of mountains, with their banded ridges and narrow valleys, resemble mountain ranges on Earth, and the loftiest peak, Maxwell Montes, rises to Himalayan altitudes, standing over 11 thousand meters above the surrounding terrain.
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Copyright 2010, Professor Kenneth R. Lang, Tufts University