Rain shower on a Cambrian mudflat

Raindrop imprints,as an ephemeral structure on the surface of loose or semi-consolidated sediments exposed to air,are charac-terized by a central depression surrounded by an external rim.These imprints are useful in interpreting the paleoenvironment and paleoclimate[1,2].One of the most fascinating is the applica-tion of raindrop imprints to estimate the paleo-air density[3,4].The paradox is that in general,raindrop imprints are easily erased by subsequent heavier downpours,waves,bioturbation,and other actions before,during,and after burial.Thus,very harsh conditions must have prevailed to preserve such imprints in ancient sedi-ments[5].For these reasons,geological records of raindrop imprints are rare and are particularly scarcely reported in marine facies.Here,we report Cambrian raindrop imprints for the purpose of presenting a detailed description of raindrop imprints on a ca.510 million years old sedimentary rock and providing an accurate picture of sharp air convection in a Cambrian mudflat environment.