The Sardo-Corsican Block (SCB) is a continental microplate in the Western Mediterranean whose present-day semi-submerged configuration is the result of complex tectonic processes. This paper synthesizes two key lines of scientific evidence to support a model of significant Neogene-Quaternary subsidence of the SCB's continental platform. First, geophysical data, specifically Bouguer gravity anomaly maps, reveal a distinct gravimetric gradient over the submerged shelves of the SCB. This pattern is consistent with crustal thinning and isostatic sinking associated with the extensional tectonics that formed the adjacent Tyrrhenian Basin. Second, geological surveys have documented extensive fields of active mud volcanoes and fluid escape structures on the submerged platform, particularly in the Sardinia Channel. These features indicate ongoing tectonic instability and the presence of overpressured sediments and deep-seated fault systems. We propose that these geological phenomena not only confirm the dynamic and subsiding nature of the region but also offer a plausible naturalistic explanation for a specific detail in ancient historical accounts. Specifically, a large-scale, seismically-triggered mud volcano eruption could account for the "impassable shoals of mud" described by Plato in Critias following the sinking of Atlantis. This paper argues that the geological reality of the SCB provides a scientifically grounded framework for re-evaluating such ancient narratives as potential echoes of real, catastrophic geological events. Keywords: Sardo-Corsican Block, Tectonic Subsidence, Bouguer Anomaly, Mud Volcanoes, Western Mediterranean, Geomythology, Plato's Atlantis.