earth science

Viséan

Viséan 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 Viséan rather than just read about it. In short: The Visean, Viséan or Visian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the second stage of the Mississippian, the lower subsystem of the Carboniferous.

Key takeaways

Viséan 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 Viséan to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Viséan from memory before moving on to harder problems.

Reference excerpt

The Visean, Viséan or Visian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the second stage of the Mississippian, the lower subsystem of the Carboniferous. The Visean lasted from 346.7 to 330.3 Ma. It follows the Tournaisian age/stage and is followed by the Serpukhovian age/stage.

Name and definitions The Viséan Stage was introduced by Belgian geologist André Dumont in 1832. Dumont named this stage after the city of Visé in Belgium's Liège Province. Before being used as an international stage, the Viséan Stage was part of the (West) European regional geologic time scale, in which it followed the Tournaisian Stage and is followed by the Namurian Stage. In the North American regional scale, the Viséan Stage correlates with the upper Osagean, the Meramecian and lower Chesterian stages. In the Chinese regional time scale, it correlates with the lower and middle Tatangian series. The base of the Viséan Stage is at the first appearance of the fusulinid species Eoparastaffella simplex (morphotype 1/morphotype 2). The type locality for the stage base used to be in a road section below the castle of Dinant in Belgium, but this type locality proved to be insufficient for the purpose of stratigraphic correlation. A GSSP has been proposed in the Luzhai Formation near Penchong in the Chinese province of Guangxi. The top (the base of the Serpukhovian and Namurian) is laid at the first appearance of the conodont Lochriea ziegleri, or at the base of the biozone of goniatite Cravenoceras leion.

Biota The Carboniferous-Earliest Permian Biodiversification Event began in the Viséan, coinciding with the start of the main phase of the Late Palaeozoic Ice Age. The late Viséan saw the widespread reappearance of metazoan reefs after their devastation during the Hangenberg Event. One of the tetrapods that lived during the Visean age was Westlothiana, a reptile-like amphibian. Though originally thought to be the earliest discovered amniote, more recent research has cast doubt on this interpretation.

Biostratigraphy The Visean contains four conodont biozones:

Lochriea nodosa Zone Lochriea mononodosa Zone Gnathodus bilineatus Zone Gnathodus texanus Zone In British stratigraphy, the Visean is subdivided into five substages. From youngest to oldest, these are:

Brigantian Asbian Holkerian Arundian Chadian (the lower part of this substage falls in the Tournaisian)

References

Further reading Dumont, A.H.; 1832: Mémoire sur la constitution géologique de la province de Liège, Mémoires couronnés par l'Académie Royale des Sciences et Belles-Lettres de Bruxelles 8 (3), VII. (in French)

External links Upper and lower time scales for the Carboniferous at the website of the Norwegian network of offshore records of geology and stratigraphy Visean, Geowhen Database The Viséan age, www.palaeos.com

Illustrations

Worked examples

Example 1 — a first encounter with Viséan

Start with the simplest possible case. Write down what Viséan 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 Viséan 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 Viséan 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 Viséan

In research: Viséan 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 Viséan 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: Viséan is common in secondary-school and first-year university syllabi. It links to neighbouring topics Carboniferous Europe, Geological ages, Mississippian geochronology, so understanding it makes those chapters shorter.
In everyday life: Look for Viséan 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 Viséan in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Viséan 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 Viséan out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Viséan in simple terms?

The Visean, Viséan or Visian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the second stage of the Mississippian, the lower subsystem of the Carboniferous.

Why does Viséan 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 Viséan?

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 Viséan.