At http://phys.org/print312566680.html … evidence of mass strandings of marine animals crop up every now and then in the fossil record. A recent example, posted here last year, came to light when a highways was being built across the Atacama Desert in northern Chile. They are said to reflect four episodes stranding – and it is being reported that toxic algae was to blame.
This is probably a case of projecting into the past something that occurs in the present. Whales and dolphins do have a habit of stranding themselves on the beach. The paper can be found in the Proceedings of the Royal Society B, February 26th (2014). I thought it apt that the site goes by the name of 'whale hill' in local parlance – a hill of fossil marine mammals (baleen whales, sperm whales, bill fishes, seals, and aquatic sloths). See also http://cerroballena.si.edu the site of the Smithsonian Institute (3D images). It emerges that only a fraction of the site was actually excavated.