Artificial illumination technique has been applied to a qualitative interpretation of a region of the aeromagnetic survey of Spanish mainland. The investigated region corresponds to a 295 x 190 km rectangle oriented N54.5'-'E which includes the Spanish segment of the Plasencia Dike. Four magnetic structures has been recognized and tentatively correlated to geological structures. The main lineament (L1) exhibit a N50E mean trend which has been associated with the Plasencia Dike. The magnetic anomaly produced by this structure presents a continuous character, although it shows lower intensity w here the dike is not outcroping. The s e c o n d ob serv ed m agnetic lineam ent (L2) presents a N S orientation, matching on surface with the Herradon fault and with La Cañada metamorphic outcrop. A third group of magnetic lineaments exhibits a E-W direction (R). These anomalies could correspond to vertical shear zones described in literature. The latest anomalies are cutand displaced by NE-SW trending structures (F) which could be correlated to the NNE-SSW Alba-Villoria fault and to the ENE-WSW Salamanca fault syste
