The Acklington Dyke is an

igneous Igneous rock ( ), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial ...

intrusion In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

which extends from northwest of

Hawick Hawick ( ; ; ) is a town in the Scottish Borders council areas of Scotland, council area and counties of Scotland, historic county of Roxburghshire in the east Southern Uplands of Scotland. It is south-west of Jedburgh and south-south-east o ...

in southern

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 ...

east-southeastwards through the Borders region towards the

North Sea The North Sea lies between Great Britain, Denmark, Norway, Germany, the Netherlands, Belgium, and France. A sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian Se ...

coast of

Northumberland Northumberland ( ) is a ceremonial counties of England, ceremonial county in North East England, on the Anglo-Scottish border, border with Scotland. It is bordered by the North Sea to the east, Tyne and Wear and County Durham to the south, Cumb ...

in northern

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

.The dyke is associated with

volcanism Volcanism, vulcanism, volcanicity, or volcanic activity is the phenomenon where solids, liquids, gases, and their mixtures erupt to the surface of a solid-surface astronomical body such as a planet or a moon. It is caused by the presence of a he ...

which took place at the

Isle of Mull The Isle of Mull or simply Mull ( ) is the second-largest island of the Inner Hebrides (after Skye) and lies off the west coast of Scotland in the Council areas of Scotland, council area of Argyll and Bute. Covering , Mull is the fourth-lar ...

igneous centre in western Scotland during the early

Palaeogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

Period at a time of regional crustal tension associated with the opening of the north

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

and which resulted in the intrusion of innumerable dykes. The similar Cleveland Dyke has been dated to 55.8+/- 0.9 Ma. The dyke is composed of

tholeiitic The tholeiitic magma series () is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic ...

microgabbro Diabase (), also called dolerite () or microgabbro, is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grained ...

and

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

Though generally thinner, it is up to 30 m wide in places. It is one of the most significant of a swarm of such intrusions associated with the Mull centre which extend southeastwards through this region, the others being the Cleveland Dyke and the Blyth and Sunderland subswarms of Northumberland and

Tyne and Wear Tyne and Wear () is a Ceremonial counties of England, ceremonial county in North East England. It borders Northumberland to the north and County Durham to the south, and the largest settlement is the city of Newcastle upon Tyne. The county is ...

. They are grouped as part of the Mull Dyke Swarm which in turn is a part of the North Britain Palaeogene Dyke Suite The dyke has been worked for roadstone at

Acklington Acklington is a small village in Northumberland, England. It is situated to the south-west of Amble, inland from the North Sea coast. It is served by Acklington railway station. The name is Anglo-Saxon Old English meaning 'farmstead of Eadlac's ...

in Northumberland.Stone, P. et al. 2010 British Regional Geology: ''Northern England'' (5th edition) (Keyworth, Nottingham. British Geological Survey) p. 243

References

{{Reflist Geology of Scotland Geology of Northumberland Magmatic dikes