 These mountain building events are known as orogenic periods, often named after the principal mountain ranges or ancient tribal areas in which the early geological research was undertaken.The Montagne Noire result largely from what is known as the Variscan (or Hercynian) Orogeny.The local geology is complex with evidence of very old rocks from the Precambrian period being distorted and overlain with ocean sediments, which in turn have been involved in massive tectonic events.