Actual knowledge on the stratigraphy and tectonics of the Jura Mountains are briefly reviewed. The hypothesis of the Jura being formed with the help of compressive forces of an alpine origin, and transmitted through the sedimentary layers of the Swiss Plateau is rejected. Instead, a model is proposed, taking into account the fracturation of the underlaying basement only. The fact that there is not any other foldings of the Jura type along the Northern rim of the Western Alps can be explained. During Upper Cretaceous times, a regional drift of the Earth's crust towards NE generated the Rhine and Bresse Grabens as well as a compression zone linking both features. Due to the first Alpine movements during early Tertiary times, part of the basement driven to the N was caught against this compression zone. A fault and fold pattern was formed and progressively developped during the Tertiary. In turn, the compression forces responsable for the building of the Jura structures reflect the Tertiary Alpine rotations of the Mediterranean area.