Here can be seen the exposed strata of sedimentary rock which were laid down on an ancient sea-bed between 140 and 30 million years ago.
The middle of this period of deposition coincides with the division between the Secondary and Tertiary periods, the so-called K/T limit (65 million years ago): there then occurred a catastrophic event which led to the disappearance of many animals, among which the land dinosaurs. The rocks, especially in the formation of the Red Scaglia, absorb small proportions of iron ore which have made it possible to do palaeomagnetic testing. From this it has been established, among other things, that the Italian peninsula, in the last 80 million years, has undergone an anti-clockwise rotation of between 50° and 70° with respect to Europe. The gorge has come to the fore because of an important discovery made in the K/T limit zone. When measuring the concentration of iridium in the Red Scaglia, a significant increase in the presence of this element in the K/T limit was noted, a finding which was later confirmed worldwide and which is probably due to an influx of extra-terrestrial material coming from the solar system. The most likely hypothesis is that a large meteorite impacted on the earth’s surface, sending into the atmosphere great quantities of dust which hung in the air for several years, absorbing important quantities of solar radiation at the expense of life cycles. The effect of this impact
was catastrophic for life on earth. Plants died for lack of light, or their growth was halted. Most of the animals which depended directly on such vegetation became extinct. Only less specialized organisms (among which the ancestral mammals) managed to survive. As well as for its great geological importance the Bottaccione Gorge is of remarkable interest from a historical and artistic point of view, in particular for the audacious mediaeval aqueduct.