Caractérisation morphokarstique de l'Igue du Gral

The Igue du Gral, as a largely vertical cavity, has functioned as a natural trap during several periods, and the distribution of the filling is linked to the opening and to the closing of entrance vents over time. The prolonged periods when it was closed allowed the good conservation of paleontological material, while the episodic karst functioning of the cavity was determined by the morpho-dynamic and climatic factors, both on the surface of the plateau and underground. The alternation of overture and closure controls the conditions of deposition, alteration, or degradation, particularly when meteorological agents cause flow conditions or, inversely, the storage of water in the form of snow. In this context, the main chamber and its surroundings constitute a key factor in the morphological dynamism of the cavity, resulting from the operation of the shafts from which the external elements (sediments, fauna, snow) come, and from the karst activity of the deeper cave. Our participation in the Igue du Gral project from 2005 to 2011 was an opportunity to develop methods for analysing a complex karst context useful for understanding the constitution of faunal groups and their evolution from the Pleistocene to the present.