Rockall Plateau
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The Rockall Trough () is a deep-water bathymetric feature to the
northwest The points of the compass are a set of horizontal, radially arrayed compass directions (or azimuths) used in navigation and cartography. A '' compass rose'' is primarily composed of four cardinal directions—north, east, south, and west— ...
of
Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...
and
Ireland Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...
, running roughly from
southwest The points of the compass are a set of horizontal, radially arrayed compass directions (or azimuths) used in navigation and cartography. A '' compass rose'' is primarily composed of four cardinal directions—north, east, south, and west— ...
to northeast, flanked on the north by the Rockall Plateau and to the south by the Porcupine Seabight. At the northern end, the channel is bounded by the Wyville-Thomson Ridge, named after Charles Wyville Thomson, professor of
zoology Zoology ( , ) is the scientific study of animals. Its studies include the anatomy, structure, embryology, Biological classification, classification, Ethology, habits, and distribution of all animals, both living and extinction, extinct, and ...
at the
University of Edinburgh The University of Edinburgh (, ; abbreviated as ''Edin.'' in Post-nominal letters, post-nominals) is a Public university, public research university based in Edinburgh, Scotland. Founded by the City of Edinburgh Council, town council under th ...
and driving force behind the Challenger Expedition. At the southern end, the trough opens into the
Porcupine Porcupines are large rodents with coats of sharp Spine (zoology), spines, or quills, that protect them against predation. The term covers two Family (biology), families of animals: the Old World porcupines of the family Hystricidae, and the New ...
abyssal plain An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between . Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth's surface. They ...
. The Rockall Basin (also known as the Hatton Rockall Basin) is a large (c. )
sedimentary basin Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock They form when long-term subsidence ...
that lies beneath the trough. Both are named after Rockall, a rocky islet lying west of St Kilda. Features of the Rockall Plateau have been officially named after features of
Middle-earth Middle-earth is the Setting (narrative), setting of much of the English writer J. R. R. Tolkien's fantasy. The term is equivalent to the ''Midgard, Miðgarðr'' of Norse mythology and ''Middangeard'' in Old English works, including ''Beowulf'' ...
in the fiction of
J. R. R. Tolkien John Ronald Reuel Tolkien (, 3 January 1892 – 2 September 1973) was an English writer and philologist. He was the author of the high fantasy works ''The Hobbit'' and ''The Lord of the Rings''. From 1925 to 1945, Tolkien was the Rawlinson ...
, e.g. Eriador Seamount, Rohan Seamount, Gondor Seamount, Fangorn Bank, Edoras Bank, Lorien Knoll, Isengard Ridge. In February 2000, the ''
RRS Discovery RRS ''Discovery'' is a barque, barque-rigged steamship, auxiliary steamship built in Dundee, Scotland for Antarctic research. Launched in 1901, she was the last traditional wooden three-masted ship to be built in the United Kingdom. Her first m ...
'', a British oceanographic research vessel sailing in the Rockall Trough encountered the largest waves ever recorded by scientific instruments in the open ocean, with a SWH of and individual waves up to .Holliday, NP, MJ Yelland, RW Pascal, VR Swail, PK Taylor, CR Griffiths, and EC Kent (2006)
Were extreme waves in the Rockall Trough the largest ever recorded?
Geophysical Research Letters, Vol. 33, L05613


Geological structure

The nature of the crust beneath the Rockall Trough has long been a matter of debate. Originally thought to be
oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramaf ...
it is now generally considered to be highly stretched
continental crust Continental crust is the layer of igneous, metamorphic, and sedimentary rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as '' continental shelves''. This layer is sometimes called '' si ...
, although some groups of researchers continue to favour either oceanic or transitional style crust, particularly at the southern end of the basin. The Rockall Basin forms part of a chain of highly extended
Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...
rift basins between the Charlie–Gibbs and Senja fracture zones, that includes; the Faroe-Shetland Basin, the Møre Basin, and the Vøring Basin. There are indications that the Rockall Basin developed within an earlier rift system, which is likely to be of
Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...
to Middle
Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...
in age, by analogy with the nearby Slyne-Erris Basins. The age of the main rift phase in the Rockall Basin is strongly debated, with Late Jurassic, Early-, Mid- and Late
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
all being suggested. During the
Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...
period, the Rockall Trough formed a seaway between the emergent Rockall-Hatton landmass (equivalent to the modern submerged Rockall Bank) and the emergent Hebrides Platform (comprising the modern
Outer Hebrides The Outer Hebrides ( ) or Western Isles ( , or ), sometimes known as the Long Isle or Long Island (), is an Archipelago, island chain off the west coast of mainland Scotland. It is the longest archipelago in the British Isles. The islan ...
). One of the features of the Rockall Trough is the Anton Dohrn Seamount. It lies beneath the surface, rising from the surrounding
seabed The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as seabeds. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...
. The plateau formed approximately 55 million years ago, a continental fragment formed between Greenland and Europe when the ancient continent of
Laurasia Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pa ...
was split apart by
plate tectonics Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...
. The Rockall Islet is the highest point of the plateau, rising 21 m above sealevel. It is made of a type of peralkaline
granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...
.


Economic geology

To date, there has been comparatively little drilling to explore for oil and gas within the Rockall Basin and only two discoveries have been made, Benbecula in the northern UK Rockall (
Shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses Science Biology * Seashell, a hard outer layer of a marine ani ...
originally Enterprise Oil) and Dooish in the northern Irish Rockall (Shell originally Enterprise Energy Ireland). The discoveries show that, at least locally, there is a working petroleum system. Rights to exploit these resources are disputed between the United Kingdom, the
Republic of Ireland Ireland ( ), also known as the Republic of Ireland (), is a country in Northwestern Europe, north-western Europe consisting of 26 of the 32 Counties of Ireland, counties of the island of Ireland, with a population of about 5.4 million. ...
,
Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...
and the
Faroe Islands The Faroe Islands ( ) (alt. the Faroes) are an archipelago in the North Atlantic Ocean and an autonomous territory of the Danish Realm, Kingdom of Denmark. Located between Iceland, Norway, and the United Kingdom, the islands have a populat ...
(a possession of
Denmark Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...
). This topic is addressed in Rockall Bank dispute.


Ecology

The area supports cold-water
coral Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...
colonies and carbonate mound fields such as the Logachev Mounds; the trough supports a rich deep sea fish population. There are also unusual aggregations of deep-sea
sponge Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...
s, in particular the encrusting sponge and bird's nest sponge. A range of other species are found amongst the sponges beds, which are considered biodiversity hotspots. For the bird's nest sponge associated species include ascidians,
Foraminifera Foraminifera ( ; Latin for "hole bearers"; informally called "forams") are unicellular organism, single-celled organisms, members of a phylum or class (biology), class of Rhizarian protists characterized by streaming granular Ectoplasm (cell bio ...
,
polychaete Polychaeta () is a paraphyletic class of generally marine Annelid, annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called c ...
s and burrowing anemones, whilst for the encrusting sponge beds species such as anemones, ascidians, crinoids and ophiuroids are found. The area is also home to brittlestars: filter feeders which live on the seabed. In 2014 an area of of the Hatton-Rockall Basin was declared a Nature Conservation Marine Protected Area. The MPA is designated a Category IV
protected area Protected areas or conservation areas are locations which receive protection because of their recognized natural or cultural values. Protected areas are those areas in which human presence or the exploitation of natural resources (e.g. firewood ...
by the
International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...
.


See also

* Hatton Basin * Porcupine Seabight * Slyne-Erris Basin


References

*R.S.Haszeldine and M.J.Russell. 1987. The Late Carboniferous northern North Atlantic Ocean: implications for hydrocarbon exploration from Britain to the Arctic. In: J.Brooks and K.W.Glennie (Eds) Petroleum Geology of North West Europe, Graham and Trotman, London, 1163–1175. *D.Naylor, P.M.Shannon and N.Murphy. 1999. Irish Rockall Basin region – a standard structural nomenclature system. Petroleum Affairs Division, Dublin, Special Publications. 1/99. *N.C.Morewood, G.D.Mackenzie, P.M.Shannon, B.M.O'Reilly, P.W.Readman and J.Makris. 2005. The crustal structure and regional development of the Irish Atlantic Margin. In: A.G.Dore and B.A.Vining (Eds) Petroleum Geology: North-West Europe and Global Perspectives – Proceedings of the 6th Petroleum Geology Conference, 1023–1033, Geological Society, London.


External links


Friendsoftheirishenvironment.net: Rockall Basin Pip.ie: Rockall Basin
{{Marine Protected Areas in Scotland Sedimentary basins of Europe Geology of Ireland Geology of Scotland Coasts of Ireland Scottish coast Rockall Geography of Ireland Geography of Northern Ireland Geography of Scotland Landforms of Ireland Landforms of Northern Ireland Landforms of Scotland Economic geology Fishing in Scotland Mesozoic rifts and grabens Nature Conservation Marine Protected Areas of Scotland Rift basins