Atmosphere and Weathering on Pandora

The atmosphere on Pandora is 20% denser than Earth’s. It is made up of roughly 18% carbon dioxide. In addition, Pandora has 20% lower gravity than Earth. This yields greater wind force, as the greater air density carries with it more kinetic energy. Because of this, weathering due to wind accounts for more of the weathering on Pandora than it does on Earth. Unlike Earth, however, the atmosphere on Pandora contains roughly 2% sulfur dioxide, caused by the multiplicity of around 180 active volcanoes which cover the moon. The high amount of sulfur dioxide causes much of the rainfall on Pandora to be acid rain. Acid rain weathers rocks at about 150% the rate of regular rain, and weathers soil at about 200% the rate. Dissolution like this is still only a small portion of rock weathering on Pandora.

The floating mountains, from which Ta buk'ne falls.

Pandora also differs from Earth in that its plants are vastly larger. The largest trees on Pandora are measured at over 1500 feet tall. (The tallest tree on Earth, Hyperion, is around 370 feet.) Plants that size have massive roots, causing an immense pressure on the rock and soil.  Rock and soil weather in this manner even on the floating mountains of Pandora. When the process occurs in large enough quantities, chunks of rock can break off of the floating mountain and fall hundreds of meters to the moon below. The locals call this phenomenon Ta buk’ne, or “falling rock.” Unseen on Earth, this extreme form of rockfall causes the talus to become a giant wrecking ball, often further weathering and eroding the ground below. Though it follows the same basic weathering patterns as Earth, these two major differences set Pandora apart.

The massive plants of Pandora.

Sources 

http://www.npr.org/blogs/krulwich/2011/04/08/135206497/the-worlds-tallest-tree-is-hiding-   somewhere-in-california

http://www.epa.gov/acidrain/

Avatar: An Activist Survival Guide by Maria Wilhelm