Further reading: Cretaceous to Paleogene stratigraphic section of Bottaccione Gorge, Gubbio
https://iugs-geoheritage.org/geoheritage_sites/cretaceous-to-paleogene-stratigraphic-section-of-bottaccione-gorge-gubbio/?fbclid=IwY2xjawUxgmhleHRuA2FlbQIxMABwZG9mBWJyaWQRMEZRbmZGcEQ3TlplN0VIcVlzcnRjBmFwcF9pZBAyMjIwMzkxNzg4MjAwODkyAAEeubLPbi_6yXsiVAp9jCB3naloNckwEPt_p-AFCfhlm5YxIW-wVs7o3frpth4_aem_B0gJGcGjBQW0hkd9AP6VZQ