Final answer:
The increase of atmospheric oxygen produced by photosynthetic organisms led to significant changes in Earth's geosphere, such as the formation of an ozone layer and the evolution of aerobic life, which in turn affected geological processes.
Step-by-step explanation:
The increase in atmospheric oxygen, largely due to the photosynthetic activities of organisms like cyanobacteria, had profound impacts on the geosphere. Prior to this oxygenation event, Earth's atmosphere was anoxic, meaning that life was primarily anaerobic. As photosynthetic organisms evolved, they began to release oxygen as a byproduct, which led to several important changes. First, oxygen reacting with minerals in Earth's crust formed new rock types and reduced the availability of certain elements that readily react with oxygen. Next, the increase in oxygen levels contributed to the formation of a protective ozone layer, which shields the Earth from harmful ultraviolet radiation, thus allowing a wider range of life forms to exist and proliferate on land. Finally, oxygen allowed for the evolution of aerobically-respiring organisms, which use oxygen to release energy from organic molecules more efficiently than anaerobic respiration. These changes in the geosphere and biosphere were interconnected, with biological evolution influencing geological processes and vice versa.