Pdf: http://geolfrance.brgm.fr/revues%5Carticles%5CGF10-1-2010.pdf

The Bathonian is the third stage of the Middle Jurassic System. Its name derives from the “Bath Oolithe” formation, cropping out in the surroundings of Bath, in southern England. However, in this country, no outcrops make it possible define the stratotype of the Bathonian Stage, as the succession is taphonomically and stratigraphically condensed. The Ravin du Bès section at Bas Auran was thus suggested as the bounding stratotype in 1967. Only later, in 1990, this section was officially proposed as possible stratotype (G.S.S.P.) of the basal boundary of the Bathonian Stage. Lastly, in 2007 this G.S.S.P. was formally accepted by the Bathonian Working Group and, in 2008, the proposal was ratified by the I.U.G.S. Three sections were studied in the surroundings of the Bas Auran farm (Alpes de Haute-Provence, France). The succession is composed of marly and calcareous beds that alternate on nearly 13 metres, and is unconformably overlain by the “Terres Noires” Formation with a sharp hard ground at the lithostratigraphic boundary. The studied interval spans the Bomfordi Subzone (Parkinsoni Zone, late Bajocian) to the Tenuiplicatus Subzone (Aurigerus Zone, early Bathonian). Recent work allowed completing and refining the existing date on ammonoid assemblages, ichnology and sedimentology. The ammonoid biostratigraphy, the microfossil and nannoplancton assemblages, the ichnologic data and, mainly, the absence of any discontinuity in the lithologic and palaeobiological records help to propose the base of bed RB71 of the Ravin du Bès section as the G.S.S.P. of the Bathonian Stage. It is noteworthy that the Bas Auran site is comprised within the Réserve Géologique de Haute-Provence; this is an important aspect that favours the protection of those sections which are very easily accessible.