Graphical abstract
Tethyshadros insularis and crocodilians struggle against a violent monsoon storm.
AI-generated image (ChatGPT 5.6 Sol)
Young-Earth creationists are fond of pointing out that a single flood or storm can deposit a layer of sediment very quickly, as though this somehow proves that the entire geological record could have been produced during the mythical year-long flood described in Genesis. But the speed with which an individual layer forms tells us nothing about the intervals between successive layers. When those layers contain regular, measurable cycles produced by processes operating daily, fortnightly and seasonally, they become a record of elapsed time—and that time cannot simply be waved away.
An article in The Conversation by palaeontologist Alfio Alessandro Chiarenza of University College London describes just such a record. It concerns the Villaggio del Pescatore fossil site near Trieste, north-eastern Italy, where dinosaurs, crocodilians, fish, shrimps, plants and other organisms were preserved with exceptional detail about 80 million years ago.
Chiarenza and his colleagues, led jointly with Federico Fanti of the University of Bologna, have published their findings in the journal Global and Planetary Change. Their evidence shows that the site was not, as previously proposed, a quiet lake or sinkhole. It was a tropical tidal flat on the edge of an ancient sea, repeatedly affected by powerful monsoon floods and tropical cyclones.
The fossil-bearing limestone consists of metre-thick packages containing thousands of discrete, paper-thin light and dark layers. These had previously been interpreted as annual deposits, or varves. However, high-resolution synchrotron X-ray scanning, microscopic and geochemical analyses, and statistical analysis of the repeating patterns revealed something still more remarkable: the layers are tidal microcouplets, laid down under a semidiurnal tidal regime—two tidal cycles each day.
Moreover, variations in the thickness of the layers follow the familiar fortnightly alternation between spring and neap tides. The rocks therefore contain not merely a succession of vaguely similar bands, but an ordered astronomical rhythm produced by the interaction of Earth’s rotation with the orbit of the Moon. By counting and analysing those layers, the researchers calculated that the fossil-bearing succession accumulated over approximately 40 years. In other words, the rock preserves an almost day-by-day record extending across four decades.
That presents creationists with a problem that cannot be dismissed by claiming that “floods can deposit sediment rapidly”. Of course they can; that is precisely what some of the layers record. But a single flood cannot manufacture 40 years’ worth of successive twice-daily tidal deposits, arranged in the correct fortnightly spring–neap pattern. Still less can the supposed year-long biblical flood accommodate a geological sequence that records some 40 years of tides within one small part of a vastly larger, 80-million-year-old succession.






