<p>The first Neogene deposits in the northern Middle Atlas are the Vallesian (Middle-Upper Tortonian) lacustrine and palustrine series of the Oued Zraa and Oued Mdaz basins. The first is part of the tabular Middle Atlas and consists of a terrigenous, conglomeratic, and micro-conglomeratic formation at the base, which is topped by volcanic and volcano-sedimentary layers sealed by marl-limestone alternations. The second basin belongs to the folded Middle Atlas, defined by micro-conglomeratic and silty-sandy deposits at the bottom, topped by marly layers and surmounted by white limestone formations. These deposits are affected by ductile and brittle soft-sediment deformation structures (SSDS), such as sedimentary veins, normal and sealed reverse faults, boudinages, symmetrical and asymmetrical folds, and load structures. The trigger mechanism investigated for these deformations, combined with the tectonic and microtectonic analyses carried out in the two basins, reveals that these hydroplastic deformations are seismic in origin and can then be defined as seismites. This tectonic activity correlate to the Vallesian tectonic phase in the Middle Atlas range, with WNW-ESE to NW-SE σ1 stress axis and NE-SW to NNE-SSW stress σ3 axis, with the permutation of axes σ1-σ2 and σ2-σ3. These tectonic activities induced the normal faulting of the Aït Choaib and Taghout Ouzemour faults, oriented NW–SE within the Oued Mdaz basin, as well as along similarly oriented faults in the Oued Zraa basin. These faults controlled the formation and evolution of both basins. The Vallesian tectonic phase is divided into two episodes: NE-SW extensional episode and NW-SE compressional one. This leads to the appearance of NE-SW reverse faults, symmetrical and asymmetrical syn-sedimentary folds, with axial planes striking in NE-SW direction.</p>