Shell middens deposited by humans typically contain shells of a very few selected (human food) species. Geophysical (tsunami) deposits generally contain a very wide -- and mixed -- assortment of shells of diverse species.
Any archaeologist worth hiring should be able to tell the difference between a midden and a geophysical deposit.
And no human (certainly no aboriginal) activity of which I am aware can create massive "chevron" landforms.
Methinks some Aussie Archies are thinking more highly of themselves than is warranted...
Shouldn't be that difficult.