earth science

Volcanic plug

Volcanic plug is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Volcanic plug rather than just read about it. In short: A volcanic plug, also called a volcanic neck or lava neck, is a volcanic object created when magma hardens within a vent on an active volcano. When present, a plug can cause an extreme build-up of high gas pressure if rising volatile-charged magma is trapped beneath it, and this can sometimes lead to an explosive eruption.

Key takeaways

Volcanic plug belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Volcanic plug to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Volcanic plug from memory before moving on to harder problems.

Reference excerpt

A volcanic plug, also called a volcanic neck or lava neck, is a volcanic object created when magma hardens within a vent on an active volcano. When present, a plug can cause an extreme build-up of high gas pressure if rising volatile-charged magma is trapped beneath it, and this can sometimes lead to an explosive eruption. In a plinian eruption the plug is destroyed and ash is ejected. Glacial erosion can lead to exposure of the plug on one side, while a long slope of material remains on the opposite side. Such landforms are called crag and tail. If a volcanic plug is later covered by softer, looser layers of tephra, such as ash and hydrothermally altered lava, then agents of erosion may in time remove that softer surrounding rock while the plug's harder, less erodible congealed magma remains, producing a distinctive upstanding, necklike landform.

Examples of volcanic plugs

Africa Near the village of Rhumsiki in the Far North Province of Cameroon, Kapsiki Peak is an example of a volcanic plug and is one of the most photographed parts of the Mandara Mountains. Spectacular volcanic plugs are present in the center of La Gomera island in the Canary Islands archipelago, within the Garajonay National Park. The Pico Cão Grande (Portuguese for "Great Dog Peak") is a landmark needle-shaped volcanic plug peak in São Tomé and Príncipe, in the Caué District of São Tomé Island in Parque Natural Obô de São Tomé. Its summit is 663 m (2,175 ft) above sea level,[1] and it rises about 370 m (1,210 ft) over the surrounding terrain.[2]

Asia Sigiriya is an ancient rock fortress near the town of Dambulla in Sri Lanka. Approximately 180m high, it is now a UNESCO listed World Heritage Site.

Europe

Borgarvirki is a volcanic plug located in north Iceland. A volcanic plug is situated in the town of Motta Sant'Anastasia in Italy. Saint Michel d'Aiguilhe chapel, whose construction started in 969, near Le Puy-en-Velay in France. The volcanic plug rises about 85 metres (279 ft) above the surroundings. Another building on a volcanic plug is the 14th century Trosky Castle in the Czech Republic. Strombolicchio, the northernmost of the Aeolian Islands, and Rockall, a small, uninhabited, remote islet in the North Atlantic Ocean, are also volcanic plugs. In the United Kingdom, two examples of a building on a volcanic plug are the Castle Rock in Edinburgh, Scotland, and Deganwy Castle, Wales. The Law, Dundee, Ailsa Craig, Bass Rock, North Berwick Law and Dumgoyne hill are other examples of volcanic plugs located in Scotland. There are over 30 volcanic plugs in Northern Ireland, including Slemish in Ballymena, Tievebulliagh, Scawt Hill, Carrickarede, Scrabo and Slieve Gallion.

North America and the Caribbean There are several volcanic plugs in the United States, including Morro Rock in California, Devils Elbow located in the Heceta Head Lighthouse Scenic State Park on the Oregon coast, Thumb Butte in the Sierra Prieta of Arizona and Agathla Peak near Monument Valley, and Shiprock and Cabezon Peak, both found in New Mexico. Devils Tower in Wyoming and Little Devils Postpile in Yosemite National Park, California, are also believed, by many geologists, to be volcanic plugs. In Canada, the Northern Cordilleran Volcanic Province gives rise to several confirmed and suspected plugs. Chief among these is Castle Rock, located in British Columbia, which last erupted during the Pleistocene. The southern coast of Saint Lucia is dominated by the iconic Pitons, a UNESCO World Heritage Site. The twin peaks, Gros Piton and Petit Piton, steeply rise more than 770 metres (2,530 ft) above the Caribbean.

South America Pinnacle Rock, Galápagos, Ecuador.

Oceania There are several volcanic plugs in the North Island of New Zealand, including:

the Pinnacles in the Coromandel Peninsula Bream Head in Northland Paritutu and the adjacent Sugar Loaf Islands in Taranaki St. Paul's Rock at Whangaroa Harbour Piha's Lion Rock, which hosted a fortified Maori pā Mount Pohaturoa near the village of Ātiamuri, a distinctive sight for travelers along State Highway 1 In New Zealand's South Island, Onawe Peninsula on Banks Peninsula is a prominent volcanic plug, and erosion of Saddle Hill near Dunedin has also revealed a plug. Dunedin's Mount Cargill displays two plugs: its main summit and the subsidiary summit of Buttar's Peak. In Australia, The Nut in Tasmania are further examples, along with Mount Warning and the several peaks in the Warrumbungles in New South Wales. The 11 peaks of the Glasshouse Mountains National Park including Mount Beerwah, Mount Tibrogargan, Mount Coonowrin, Mount Cooroora, Mount Ngungun, Mount Tibberoowuccum, Mount Tunbubudla, and Mount Beerburrum, in South East Queensland are volcanic plugs.

Gallery

References

Illustrations

Worked examples

Example 1 — a first encounter with Volcanic plug

Start with the simplest possible case. Write down what Volcanic plug claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Volcanic plug before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Volcanic plug ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Volcanic plug

In research: Volcanic plug appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Volcanic plug in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Volcanic plug is common in secondary-school and first-year university syllabi. It links to neighbouring topics Volcanic landforms, Volcanic plugs, so understanding it makes those chapters shorter.
In everyday life: Look for Volcanic plug outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Volcanic plug in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Volcanic plug means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Volcanic plug out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Volcanic plug in simple terms?

Why does Volcanic plug matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Volcanic plug?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Volcanic plug.