When new clay sediment is deposited on top of old beach material, it's known as

A. progression.

B. aggression.

C. transgression.

D. regression.

When new clay sediment is deposited on top of old beach material, it's known as. C. transgression. This is because the clay would have to come from sea inundating the beach ie rising and depositing the clay on the old beach. The sea rising could be from say tectonic movement or from glaciers melting but before glacial rebound.

It is known as C. Transgression