Geology
The Burin Peninsula is part of the Avalon Zone of the Appalachian Orogen, the geology of which chronicles the late Precambrian Alleghenian Orogeny. The stratigraphy is not uniform throughout the region, however. The southern end of the peninsula includes a series of mafic pillow lavas, volcanigenic sediments, shales and limestones, collectively known as the "Burin Group", as well as a 1500 m thick sill of gabbro about 760 million years old. The northern end of the peninsula is defined by the "Marystown Group", primarily carbon-lacking Silica-based sediments which span the Precambrian-Cambrian boundary. The sediments were probably deposited in shoreline environments along the former Iapetus Ocean.
The global stratotype at Fortune Head is composed of the uppermost part of member 1 and all of member 2 of the Chapel Island Formation of the Marystown Group. The Chapel Island Formation consists primarily of sandstones, siltstones, and limestones. Some of these rocks exhibit mud cracks and stromatolites, suggesting that deposition occurred in tidal or, at deepest, continental shelf environments.
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