Prevalent Lebensspuren on Beaches of the Mediterranean Coast of Languedoc, France, and the Influence of the Winds on Their Preservation

DEMATHIEU, GEORGES R., University of Dijon, Bourg-la-Reine, France

The beaches considered herein are located between the town of Palavas (Herault) and the Petit Rhone (Gard).

They are of a very fine (less than 1/10 mm) siliceous sand (85%). As the Mediterranean Sea does not present obvious lunar tides, variations of sea level are due to variations of the barometric pressure. Also, large parts of the beaches can sometimes overflow.

Two realms must be distinguished: one, always wet, can be very large; the other, dry, comprises small dunes.

The ichnocoenose reveals a poor fauna limited to small animals, vertebrates and invertebrates, living in the dunes; the watery part is a pathway used by other creatures.

If the traces in dry sand are more or less promptly destroyed after a rounding of the shape, in the watery part of the beach, they undergo many changes owing to the effect of the winds. Under their influence, the shape of the traces is considerably modified: for instance, horse footprints become tridactyl, dog prints tend to be chirotherioid, simple tunnels of worms become double, or natural molds can change into casts (inverted reliefs).

The transformations produced by the winds over the ichnites show the instability of these remains when they are not quickly consolidated. If the consolidation appears after the transformations, in the future misinterpretations are possible.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)