On the basis of the active quarries in Umbria in 1976 were 277; 225 located in the district of Perugia and 52 in the district of Terni. In 1954 active quarries lessened especially in the district of Perugia while in the district of Terni the number is still constant with a high concentration in the communes of Orvieto, Narni and Terni. The extracted material comes mainly from complexes of outcropped rocks from dregs and lakes, from recent floods and calcareous rocks. In Umbria, the extracted materials are mainly employed on the spot (45,2%) in the whole region (36,2%) while 18,6% is exported out of the region (tufi, basalt and travertins). |