Identification des sables vacuolaires à terre et en mer

ABSTRACT Soft sands are due to a sponge like structure: air bubbles are trapped in sand when the area is flooded by the rising tide. This process affects the superficial sediments until a maximum depth of 60 cm. Such sands have been identified for the first time, under water, using a “Seistec” boomer. The data are compared to results acquired on Omaha Beach. Three factors conditioning soft sand occurrence are usually described in litterature: grain-size, water content, tidal variations on beach with a maximum slope dip of 8°. In this paper we outlight a fourth parameter: the local morphology which is able to highly improve the air bubble trapping.