The villages remain mainly unspoilt with small scale farming the principal source of employment. Industry, primarily paper-making, is confined to the bottom of the valleys as only there is it possible to build roads suitable for heavy vehicles. The northern, more mountainous, part of the region is known as the Garfagnana. This region begins around thirty kilometres north of Lucca. Through this area runs the river Serchio which divides two mountain ranges, the Apennines, the range that runs almost the entire length of Italy, and the Apuan Alps, the smaller coastal range well known for its marble. From this area the Serchio runs south eventually entering the Mediterranean Sea south of Viareggio.