The valleys of Santerno, Senio, Sintria and Lamone that furrow the Apennines in the western part of Romagna, are intersected, about ten kilometers from the line of junction with the plain, by the Vena del Gesso Romagnola.

It is a ridge of calcium sulphate, variously crystallized and stratified in imposing banks, which emerges for a length of about twenty kilometers and with a width that never exceeds one kilometer, crossing six municipalities including Riolo Terme.

The chalky-sulphurous formation has influenced the construction of the landscape that extends all around, favorably influencing the microclimate of the four valleys.

It is a natural and historical wealth that surprises and fascinates the hiker who walks along the paths of the Park. 

“The candidacy – we read in the motivation – is based on criterion VIII of the 1972 Convention which refers to extraordinary evidence of the main periods of the earth's evolution and concerns an area rich in evaporite deposits that generate karst forms, particularly significant for the study of the breakup of the supercontinent Pangea which occurred approximately 200 million years. The entire complex constitutes the first and most studied evaporite karst in the world."