Author 'Lustgarten' (Id 129791 ) : Geological time is measured in millions of years and is divided into eras, which are themselves divided into ages. The transition from one era to another is usually marked by a sharp change in facies that we see here . On the red sandstone from the Permian age (primary age), there are conglomerates distinct Triassic (Mesozoic). The transition took place there 250 million years. This passage is very clear between the two geological layers.