During the intense debates between fixism and mobilism, Chinese geologist J.S. Lee published “The Fundamental Cause of Evolution of the Earth’s Surface Features” in 1926 in the Bulletin of the Geological Society of China, supporting mobilism. He attributed continental movements to the variations of the Earth’s rotation speed: when the rotation speed increases, it generates forces that compel the continents and seawater to move horizontally from the poles toward the equator and vice versa. It was on this idea that his Geomechanics was established in the following decades. Lee was the most influential geologist in 20th-century China, and Geomechanics was China’s most prevalent geological theory, especially during the Cultural Revolution. In the early 1970s, Plate Tectonics theory was introduced into China, and the status of Geomechanics was replaced eventually. This paper provides a historical analysis of Lee’s initial conception of Geomechanics by introducing his first publication on geotectonics with annotated excerpts from it.