Graptolite Island
Geology
The bedrock of Graptolite Island consists entirely of a geologic unit known formally as the Greywacke Shale Formation. It consists of beds of Permian to Triassic sandstone (feldspathic arenite and feldspathic wacke) interbedded with beds of siltstone, mudstone, and diamictite. These beds were deposited by turbidity currents as turbidites in submarine fans and later metamorphosed to between anchizone to upper greenschist-facies during the late Triassic and early Jurassic.
Graptolite Island, like the rest of the South Orkney Islands, is the surface expression of the otherwise submerged South Orkney Microcontinent. This microcontinent is the biggest fragment, 250 km × 350 km (160 mi × 220 mi), of continental crust of the South Scotia Ridge lying between Antarctic and Scotia plates.
Important Bird Area
The island, along with the nearby Ferrier Peninsula, has been identified as an Important Bird Area (IBA) by BirdLife International because together they support a large breeding colony of about 91,000 pairs of Adélie penguins as well as 14,000 pairs of chinstrap penguins.
See also
References
- ^ "Graptolite Island". Geographic Names Information System. United States Geological Survey, United States Department of the Interior. Retrieved 3 May 2012.
- ^ Stewart, J., 2011. Antarctica: An Encyclopedia, 2nd ed. Jefferson, North Carolina and London, McFarland & Company, Inc. 1771 pp. ISBN 978-0-7864-3590-6
- ^ Stone, P., 2003, Fossils from the South Atlantic: the geological legacy of the Scottish National Antarctic Expedition, 1902-1905. The Edinburgh Geologist. 41, pp. 10–15.
- ^ Dalziel, I. W. D. 1979. The mythical graptolites of the South Orkney Islands. The Edinburgh Geologist. 6, pp. 2-9.
- ^ Flowerdew, M.J., Riley, T.R. and Haselwimmer, C.E., 2011. Geological Map of the South Orkney Islands. British Antarctic Survey GEOMAP 2 Series, Sheet 3, 1:150 000 scale. Cambridge, United Kingdom, British Antarctic Survey.
- ^ Busetti, M., Zanolla, M., and Marchetti, A., 2000. Geological structure of the South Orkney microcontinent. Terra Antartica, 8(2), pp. 1-8.
- ^ "Ferrier Peninsula / Graptolite Island, Laurie Island". BirdLife data zone: Important Bird Areas. BirdLife International. 2012. Retrieved 21 December 2012.
60°44′S 44°28′W / 60.733°S 44.467°W