Enige gegevens met betrekking tot de herkomst van fossiele schelpen in het Zuid-Sloe

For many years in the beginning of this century fossil shells of Pliocene origin were regularly deposited on the eastern beach of the mouth of the Sloe, a branch of the Westerschelde, a few miles upstream from Flushing. These shells originated from a layer of crag shells, forming an underwater platform at about 18.50 m depth (Fig. 3). In the year 1800 this platform was covered by an extensive deposit of young marine sand, about 18 m thick, but in course of time the Honte, one of the principal gullies of the Westerschelde, by moving in northward direction, has scoured away the young marine sand and eroded gradually the bed of crag fossils, so that at present, in 1960, the Tertiary shells are no longer washed ashore (Fig. 1 and 2). A similar case of upward transport of shells took place in 1959 between Ellewoutsdijk and Terneuzen, several miles upstream from the Sloe. This time a huge ridge of recent Cardium edule shells was formed at the eastern end of the Middelplaat (Fig. 4 and pl. 1 fig. 1). Between November 1960 and April 1961, however, the current of the Westerschelde destroyed this shell ridge completely. In both instances a transverse component of the current, combined with ground waves, worked the shells upwards along an underwater slope, while the surf finally deposited them on the beach or sandflat.