earth science

Turonian

Turonian 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 Turonian rather than just read about it. In short: The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous Epoch, or a stage in the Upper Cretaceous Series. It spans the time between 93.9 ± 0.2 Ma and 89.8 ± 0.3 Ma (million years ago).

Key takeaways

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

Reference excerpt

The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous Epoch, or a stage in the Upper Cretaceous Series. It spans the time between 93.9 ± 0.2 Ma and 89.8 ± 0.3 Ma (million years ago). The Turonian is preceded by the Cenomanian Stage and underlies the Coniacian Stage. At the beginning of the Turonian an oceanic anoxic event (OAE 2) took place, also referred to as the Cenomanian-Turonian boundary event or the "Bonarelli Event". Sea level fall took place in the latter part of the Turonian from the highstand at the beginning of the Turonian.

Stratigraphic definition

The Turonian (French: Turonien) was defined by the French paleontologist Alcide d'Orbigny (1802–1857) in 1842. Orbigny named it after the French city of Tours in the region of Touraine (department Indre-et-Loire), which is the original type locality. The base of the Turonian Stage is defined as the place where the ammonite species Watinoceras devonense first appears in the stratigraphic column. The official reference profile (the GSSP) for the base of the Turonian is located in the Rock Canyon anticline near Pueblo, Colorado (United States, coordinates: 38° 16' 56" N, 104° 43' 39" W). The top of the Turonian Stage (the base of the Coniacian) is defined as the place in the stratigraphic column where the inoceramid bivalve species Cremnoceramus rotundatus first appears.

Subdivision The Turonian is sometimes subdivided in Lower/Early, Middle and Upper/Late substages or subages. In the Tethys domain, it contains the following ammonite biozones:

zone of Subprionocyclus neptuni (in the Upper Turonian) zone of Collignoniceras woollgari (in the Middle Turonian) zone of Mammites nodosoides zone of Watinoceras coloradoense or Watinoceras devonense (last two both in the Lower Turonian) Other important index fossils are species of the inoceramid genus Inoceramus (I. schloenbachi, I. lamarcki and I. labiatus). Inoceramids are bivalve Mollusca related to today's mussels.

References

Literature Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press. Kennedy, W.J.; Walaszczyk, I. & Cobban, W.A.; 2005: The Global Boundary Stratotype Section and Point for the base of the Turonian Stage of the Cretaceous: Pueblo, Colorado, U.S.A., Episodes 28(2): pp 93–104.

External links GeoWhen Database - Turonian Late Cretaceous timescale, at the website of the subcommission for stratigraphic information of the ICS Stratigraphic charts of the Cretaceous: [1] and [2], at the website of Norges Network of offshore records of geology and stratigraphy Turonian Microfossils: 48 images of Foraminifera

Illustrations

Worked examples

Example 1 — a first encounter with Turonian

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

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

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

Frequently asked questions

What is Turonian in simple terms?

Why does Turonian 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 Turonian?

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 Turonian.