Geology
The exact position of Rockall and the size and shape of the Rockall Bank was first charted in 1831 by Captain A.T.E. Vidal, a Royal Navy surveyor. The first scientific expedition to Rockall was led by Miller Christie in 1896 when the Royal Irish Academy sponsored a study of the flora and fauna. They chartered the Granuaile.
The RV Celtic Explorer surveyed the Rockall Bank and North West of Donegal in 2003. The ILV Granuaile was chartered by the Geological Survey of Ireland (GSI), on behalf of the Department of Communications, Marine and Natural Resources (DCMNR), to conduct a seismic survey at the Rockall and Hatton Banks in July 2004. The seismic survey was part of the National Seabed Survey which has been ongoing for four years.
Rockall is made of a type of peralkaline granite that is relatively rich in sodium and potassium. Within this granite are darker bands richer in the alkali pyroxene mineral aegirine and the alkali amphibole mineral riebeckite. The dark bands are a type of granite that geologists have named "rockallite", although use of this term is now discouraged. In 1975, a new mineral was discovered on Rockall. The mineral is called bazirite, (chemical composition BaZrSi3O9), named after the elements barium and zirconium. Rockall forms part of the deeply eroded Rockall Igneous Centre that was formed as part of the North Atlantic Igneous Province, approximately 55 million years ago, when the ancient continent of Laurasia was split apart by plate tectonics. Greenland and Europe separated and the north-east Atlantic Ocean was formed between them.
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