It is well known that climatic factors can influence the degradation of rocks in different geographic environments, thus affecting the durability of natural construction materials. Research has been carried out to assess the current state of natural degradation of an Oligocene-Miocene lithic greywacke occurring without appreciable lithological and mineralogical variations from, NW to SE in Tuscany (northern Italy), considering 52 rocky outcrops distributed from approximately N 44° to N 43°. For each outcrop, the Schmidt Hammer “rebound” values (SH), which are directly proportional to the rock compressive strength, and the natural logarithm of the average annual solar radiation by geographic coordinates according to the Italian National Board for New Technology Energy and the Environment Atlas (ENEA) in M J /m2/y (LN values), were evaluated. The results showed a significant relationship between the SH and LN: the SH values decrease significantly when passing from the cold and humid areas to the hottest and dry ones. Moreover, considering the values of the average air thermal excursion of each year in degrees centigrade, it is noteworthy that these can be divided into two groups (excursion < 7.8 and excursion >= 7.8 °C) which in relation to the SH give rise to more significant distributions similar to the relation between the SH and LN. We, therefore conclude that solar radiation, and thermal excursion, in particular, are responsible for the lower mechanical strength that occurs in the warmer and drier areas, as opposed to that in the colder and moister northern zones. The research also demonstrates that sandstone degradation processes due to thermal stress are not exclusive to arid and semi-arid areas, but they also occur in a reduced form, in temperate areas.

It is well known that climatic factors can influence the degradation of rocks in different geographic environments, thus affecting the durability of natural construction materials. Research has been carried out to assess the current state of natural degradation of an Oligocene-Miocene lithic greywacke occurring without appreciable lithological and mineralogical variations from, NW to SE in Tuscany (northern Italy), considering 52 rocky outcrops distributed from approximately N 44° to N 43°. For each outcrop, the Schmidt Hammer “rebound” values (SH), which are directly proportional to the rock compressive strength, and the natural logarithm of the average annual solar radiation by geographic coordinates according to the Italian National Board for New Technology Energy and the Environment Atlas (ENEA) in M J /m2/y (LN values), were evaluated. The results showed a significant relationship between the SH and LN: the SH values decrease significantly when passing from the cold and humid areas to the hottest and dry ones. Moreover, considering the values of the average air thermal excursion of each year in degrees centigrade, it is noteworthy that these can be divided into two groups (excursion < 7.8 and excursion >= 7.8 °C) which in relation to the SH give rise to more significant distributions similar to the relation between the SH and LN. We, therefore conclude that solar radiation, and thermal excursion, in particular, are responsible for the lower mechanical strength that occurs in the warmer and drier areas, as opposed to that in the colder and moister northern zones. The research also demonstrates that sandstone degradation processes due to thermal stress are not exclusive to arid and semi-arid areas, but they also occur in a reduced form, in temperate areas.