At a given locality, a time-rock unit containing abundant fossil calcareous sponges and calcareous algae is conformably overlain by a time-rock unit containing siliceous sponges and cephalopods.
What statement can be made about bathymetric change at the locality?

Check the explanation

Explanation:

A drastic bathymetric change (which is typically created to assist in the safety of sub-surface or surface navigation, it also usually show seafloor release or terrain as contour lines and some selected depths i.e soundings, and naturally also supply surface navigational information.) that caused the water levels to drop.