Aerial prospections were performed during automn, winter or, on occasion, at the beginning of spring on ploughed and prepared or even on recently sown fields. Many ancient and coherent plot systems on areas from 5 to 200 hectares were detected in the median zone of the Nohain river valley (a Loire affluent) and its flowing or dried affluents. The peripheral zone of this valley shows a fairly different aspect devoid of such boundaries except on its south-western border in Saint-Martin-sur-Nohain and eastern part of Tracy-sur-Loire. The plot systems are diversely oriented and contiguous and seldom superimposed. Archaeological structures were located in the same zone. At the present time no relation be established between quadrilateral protohistoric enclosures or gallo-roman villae on the one hand and one or more of these parcel systems on the other hand. Therefore dating possibilities for these plots are difficult to formulate ; excavation of their boundary ditches in order to find dated artefacts may remain improductive.