A 140 m (460 ft) thick section of rock along its cliffs is the Global Boundary Stratotype Section and Point (GSSP). It represents the boundary between the Precambrian era and the Cambrian period, 541 million years ago. Because of its accessibility (easy to get at) and many fossils, Fortune Head was selected in 1992 over similar rock sections in Siberia, Russia, and Meischucum, China.
Ecological Reserve[change | change source]
Fortune Head was given full ecological reserve status in 1992 after its selection as the global stratotype. The reserve is 2.21 km2 (0.85 sq mi) in size. The Fortune Head lighthouse also acts as a visitors center.
Geology[change | change source]
The Burin Peninsula is part of the Avalon Zone of the Appalachian Orogen, a late Precambrian episode of mountain-building. The stratigraphy is not uniform throughout the region, however. The sediments were probably deposited in shoreline environments along the former Iapetus Ocean.
The global stratotype at Fortune Head is made up of sandstones, siltstones, and limestones. Some of these rocks have mud cracks and stromatolites, suggesting that deposition occurred in tidal or, at deepest, continental shelf environments.
Fossils[change | change source]
The boundary between the Precambrian and Cambrian is marked by the presence of trace fossils of Treptichnus pedum, one of the earliest animals. Treptichnus is known only by its distinctive burrow pattern, which can be seen at Fortune Head.
Fortune Head records the beginning of a period of increasing biological diversity known as the "Cambrian explosion". It has a number of other Cambrian and Precambrian fossils, including early shell fossils, vendotaenid algae, soft-bodied megafossils, and microfossils. Below Treptichnus, the stratotype at Fortune Head includes traces of the arthropod Monomorphichnus. More complex fossils appear later.