During the Tertiary era, the area where San Marino lies was the sea. Violent earthquakes caused major upheavals in the Earth's surface. Because of these intensive earthquakes, a mass of rock situated about from the mountain, was lifted and slid slowly toward the Adriatic Sea. This mass of rock gave rise to various mountains, including Mount Titano. The vertebrate fossils found on the slopes of Mount Titano are mostly aquatic in origin, because of the fact this rock was once located underneath the sea in its current spot. Fossils of various fish, especially the fossils of shark teeth have been discovered on Monte Titano, with many dated to the Miocene period. The most important fossil discovery is that of a whale, which is now preserved in the Bologna Archaeological Museum.