The Museum of Geology developed from the collection of rocks and fossils of the Roman doctor and naturalist Giuseppe Ponzi (1805-1885), the first holder of the chair of Geology founded by Pious the Ninth in 1864. It was further enlarged by the acquisition of the geologic and paleontologic collections yielded by the Kircherian Museum. The current set up of the exhibition documents the main Italian geologic formations and the formation of rocks through the volcanic activities or the erosion of the land surface. It also keeps two important collections of ancient marbles, the Accordi and the T. Belli. The former presents about 600 splendid specimens of ornamental and decorative rocks such as oriental alabasters, cipolins, granites, and marbles, while the latter consists of about 800 pieces of marbles coming from the monuments of ancient Rome and from various European localities.