Answer:
Photosynthetic organisms was the reason of these atmospheric changes.
Explanation:
The plant which is discovered by the scientists that is apparently devoid of life but has ice caps located at the poles which reveals that planet's atmospheric O₂ levels sharply increased about 1,000,000 years ago was due to evolution of photosynthetic organisms like cyanobacteria etc which went extinct and then O₂ levels dropped quickly 50,000 years ago. So photosynthetic organisms was the reason of these atmospheric changes.
Http://www.skwirk.com/p-c_s-57_u-183_t-490_c-1797/sa/7/shaping-mountains-weathering/erosion-and-r check out this source.
The two main power units for the tectonic cycle are the Sun and the interior of the Earth's core. These affect almost all changes of the lithosphere.
<span>They move from west to east by the Prevailing Westerlies and Jet Streams</span>
