The park's museum features exhibits about the fossils and paleontology of the park. The museum's collection includes over 9000 specimens of fossil fish and plants.
The coastal cliffs are made up of grey sedimentary rock (composed of alternating layers of sandstone and shale) which are 350–375 million years old. The area supports mainly birch, aspen, and fir forests. Some of the fish, fauna, and spore fossils found at Miguasha are rare and ancient species. For example, Spermasposita is thought to be one of the oldest flowering plant species on earth.
The fossil site was first discovered in 1842, by Abraham Gesner (1797–1864), a geologist and medical doctor, and a pioneer in the petroleum industry. Gesner found a vast array of important fossils, which were handed over to the British Museum and the Royal Scottish Museum; these discoveries caused great excitement throughout the world. There was a rumour in the 1970s that some Americans were seeking to purchase the land containing the fossil deposits. In 1985 the Québec government blocked this possible privatization by purchasing a large tract of the land and declaring it a provincial (called "national" in Québec) park. The peripheral area is owned by ~100 people who limit development, protecting this important site. To date, over 5000 fossils from this one site have been identified and categorized. It was declared a World Heritage Site in 1999.