Résumé
Plateaus on the western bank of the River Niger are covered with heaps and lines of dry stone although these tabular areas are now without any agriculture. A sandy clay soil horizon is present only in the areas where these structures are located, suggesting that they result from removing stones to improve the soil. The materials extracted were placed in lines or in heaps when there were too many stones. These plots could be contemporary with metallurgical activities located at the foot of plateaus and dated from the second half of the first millennium.