Event type:
Lecture, Virtual event
Organised by:
Geological Society Events
Event status:
EVENT CLOSED
From catastrophism back to uniformitarianism
When penetrating hundreds of meters into the soft sediment carpet of the three-kilometers-deep Mediterranean in the summer of 1970 a hard formation was suddenly encountered, too early to be bedrock. The drillship Glomar Challenger shook violently as the drill bit bounced and then became stuck. Only after hours of effort was the pipe freed. In its bit were gypsum that had precipitated on evaporating salt pans under temperatures exceeding 50°C and shells of molluscs that had lived in shallow freshwater lakes. The overlying sediments in previous cores had accumulated in ultra-deep water of normal ocean salinity.
Nevertheless, subsequent drill sites provided additional evidence of fossilized algal mats and plant-adhering diatoms requiring sunlight. For the shipboard scientists it became abundantly clear: five and a half million years ago the Mediterranean Sea had dried out and was then flooded with saltwater, pouring in from a cataclysmic opening of the Gibraltar Strait. Charles Lyell’s paradigm of “natural processes still in operation today” was under assault by catastrophism.
The publication of these observations in the journal Nature created much initial controversy. The desiccation hypothesis achieved a broader acceptance only after subsequent drilling expeditions and lots of attention to strata of the same age accessible in terrestrial outcrops and in the walls of deep mines.
This lecture will take us through this five-decade journey of research, that in just the last few years rehabilitates Charles Lyell. We will uncover evidence of desiccation and flooding “in operation today” elsewhere in the Dead Sea.
Speaker
Dr William B. F. Ryan - Lyell Medallist Winner 2022
Dr William Ryan's scientific career began in 1961 on an expedition to the Mediterranean Sea where a buried layer of salt was discovered. After completing his PhD from Columbia University, Dr Ryan participated in the first deep-sea drilling in the Mediterranean to sample the salt. In 1970, he became a research scientist at the Lamont-Doherty Earth Observatory of Columbia University until retirement in 2014.
His research includes investigations of mid-ocean ridges, submarine canyons, underwater volcanoes and escarpments of limestone that are our planet’s tallest cliffs. Dr Ryan's team developed deep-towed, side-looking sonar that located the RMS Titanic far from its distress position. They then used then this instrument to image seabed volcanic lava flows, giant landslides, grooves left behind by ice-age icebergs, and deformation, where one tectonic plate slides beneath another.
Dr Ryan taught at Columbia in marine geology and geophysics, plate tectonics, earth environmental systems and paleoceanography. His research in the Black Sea led to a book co-authored with Walter Pitman, titled Noah's Flood: The New Scientific Discoveries about the Event that Changed History. He is a Fellow of the American Geophysical Union and a foreign member of the Bulgarian Academy of Sciences and the Accademia Nazionale dei Lincei in Rome.
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