discontinuous in its morphology, with stretches where the Alpine/Apennine ridge is extremely compact and high aligning very high mountain groups (north to Ventimiglia, a series of massifs which became French after the Second World War, rises up to altitudes of 2700-3000 m) while in other stretches (for example in the hinterland of Savona and Genoa) the mountain barrier is not very high and deeply crossed by short valleys and passes that do not reach 500 m above sea level (Bochetta di Altare, Passo dei Giovi, Crocetta d'Orero). The winding arched extension goes from Ventimiglia to La Spezia. Of this, are mountainous (65% of the total) and are hills (35% of the total). Liguria's natural reserves cover 12% of the entire region, or of land. They are made up of one national reserve, six large parks, two smaller parks and three nature reserves. The continental shelf is very narrow and so steep it descends almost immediately to considerable depths along its coastline. Except for the Portovenere and Portofino promontories, the coast is generally not very jagged and is often high. At the mouths of the biggest watercourses are small beaches, but there are no deep bays and natural harbours except at Genoa and La Spezia. The hills lying immediately beyond the coast together with the sea account for a mild climate year-round. Average winter temperatures are and summer temperatures are , which make for a pleasant stay even in the dead of winter. Rainfall can be abundant at times, as mountains very close to the coast create an orographic effect. Genoa and La Spezia can see up to of rain in a year; other areas instead show the normal Mediterranean rainfall of annually. History Prehistory Copper begins to be mined from the middle of the 4th millennium BC in Liguria with the Libiola and Monte Loreto mines dated to 3700 BC.. These are the oldest copper mines in the western Mediterranean basin. The foundation of Genoa The Genoa area has been inhabited since the fifth or fourth millennium BC. In ancient times this area was inhabited by Ligures (ancient people after whom Liguria is named). According to excavations carried out in the city between 1898 and 1910, the Ligure population that lived in Genoa maintained trade relations with the Etruscans and the Greeks, since several objects from these populations were found. In the 5th century BC the first town, or oppidum,