AbstractArchaeological data from the lower Red River in Louisiana indicate that the modern course of the river is 1200 years older than previously suggested. Geologists claim a diversion of Red River through Moncla Gap approximately 500 to 1000 years ago. Marksville period occupations dating prior to A.D. 200 are identified at archaeological sites adjacent to the river below Moncla Gap. The position of these sites on Red River levees demonstrate that they post‐date the river's occupancy of the area. Extensive Marksville and later prehistoric occupations in the Moncla Gap area are seen as a direct result of the development of riverine environments resulting from this diversio