Caltanissetta
Caltanissetta (kaltanisˈsetta; Nissa or Cartanissetta) is a comune in the central interior of Sicily, Italy, and the capital of the Province of Caltanissetta. Its inhabitants are called Nisseni. In 2017, the city had a population of 62,797. It is the 14th largest comune in Italy measured by area, the sixth highest comune in Italy by elevation (568 m), the second highest elevation in Sicily after the city of Enna (912 m). Its patron saint is Archangel Michael. The town lies in an area of rolling hills with small villages and towns, crossed by the river Salso. It borders on the municipalities of Canicattì, Delia, Enna, Marianopoli, Mazzarino, Mussomeli, Naro, Petralia Sottana, Pietraperzia, San Cataldo, Santa Caterina Villarmosa, Serradifalco and Sommatino. Its frazioni are the villages of Bifaria, Borgo Petilia, Borgo Canicassè Casale, Cozzo di Naro, Favarella, Prestianni, Villaggio Santa Barbara, Santa Rita and Xirbi. Caltanissetta dominates the whole valley of the river Salso, which extends to include the nearby Enna. Morphologically it matches the surrounding area, very harsh and composed of limestone and clay. The city lies between three hills (Sant'Anna, Monte San Giuliano, and Poggio Sant'Elia), which form a basin which comprise part of the historical centre and South. The Maccalube (singular: Maccaluba, from Arabic مقلوبة maqlūbah, '(a land) that turns over', from the verb قلب qalaba 'to turn over, to turn upside down, to invert') are a particularly rare phenomenon of sedimentary volcanism occurring in the Terrapelata area of Caltanissetta, the so-called Hill of the Volcanoes, near the village of Santa Barbara. This is an area of barren hills, with a colour ranging from white to dark grey, where mud volcanoes of around one meter in height rest on volcanic sediment. The phenomenon is related to the presence of extensive underground clay deposits, interspersed with layers of salt water. Maccaluba is created by ejection of methane gas bubbles under pressure. When gas breaks through the clay deposits, it creates channels as it rises to the surface.