How do clay-rich rocks create calanchi badlands in Basilicata and Sicily?

The calanchi, or badlands, found in Basilicata and Sicily are primarily the result of the region's specific geological composition and susceptibility to erosion.

These landscapes are formed in areas characterized by extensive argillaceous, or clay-rich, rock types. These sedimentary units were deposited during the Plio-Pleistocene epoch as the sea regressed and transgressed along the slopes of the rising Apennine Range.1

Because these clayey rocks are highly susceptible to weathering and water runoff, they undergo frequent erosion, which strips away the surface and prevents the development of stable soil or vegetation. This process creates the characteristic "thirsty and desolate" appearance of the badlands, defined by deep gullies and sharp, barren ridges.1