During the 1930s, the shells were harvested and crushed to provide grit for poultry. Collector Ahmed loaded his calcareous loot onto camels for the journey to Portland. His diligent work soon reduced the bank of shells.
The material comes from two sources. Dunes contain shells that were washed ashore when the sea level was higher than it is now. They form distinct layers in the sand. These shells are returned to the beach when the dunes are eroded in rough weather. Most of that material is fragmented. Ready-made grit.
Lower down on the beach are recently dead shells that have been cast up from sea floor. There are plenty of bivalves but the most abundant species is the gastropod Bankivia fasciata. In Australian Seashore, William Dakin wrote of this species 'Once recognized, this shell will not be easily forgotten'. The patterns are varied and distinctive. Bankivia is known as a kelp shell but is actually a sand dweller. Although not often seen alive, it must be around in great numbers given its presence on the strandline.
Next time, I'd like to visit on a low tide with a hand lens so I can search for micromolluscs and a bivalvologist to identify those funny two-shelled things. Now that's my idea of good day on the beach.
