Geological Evidence for the Mountain-Cutting Phenomenon of the Yangtze River and Its Tributaries in the Sichuan Basin, and the Limitations of Traditional Genetic Theories ——On Prehistoric Civilization’s Geological Modification of River Systems
[Objective] To reveal the formation mechanism of the unique landform that the Yangtze River and its tributaries cut straightly and transversely through intact, hard bedrock mountain ranges in the Sichuan Basin, and identify inherent contradictions in traditional fluvial geomorphology theories. [Methods] Based on field geological surveys, evolutionary chronology and dating data of Paleo-Shu Lake, regional paleogeographic reconstruction was carried out. A multi-dimensional evidence chain was built via global geomorphic comparison, collation of ancient documents, and analogy of worldwide prehistoric bedrock engineering. [Results] The rigid chronological sequence of “mountain formation prior to lake formation, followed by lake recession and river emergence” in the study area is clarified, and six major traditional natural genesis hypotheses are disproved. The mountain-cutting landform has regular geometry without through-going structural fracture zones, and sedimentary records conflict with natural erosion models, showing analogies to global large-scale prehistoric bedrock engineering. [Limitations] This study is an exploratory interdisciplinary hypothesis, and no direct physical relics of prehistoric engineering in this drainage basin have been discovered; comparable cases of basin-scale geological modification projects of the same magnitude globally are scarce. [Conclusions] The transverse mountain-cutting landforms in the Sichuan Basin cannot be explained by conventional natural geological processes. They can be interpreted as relics of basin-scale geological modification projects for flood diversion implemented by a prehistoric high-technology civilization, offering a new paradigm for interdisciplinary research of geomorphology and prehistoric civilization.
