earth science

Kimmeridgian

Kimmeridgian 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 Kimmeridgian rather than just read about it. In short: In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 154.8 ±0.8 Ma and 149.2 ±0.7 Ma (million years ago).

Key takeaways

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

Reference excerpt

In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 154.8 ±0.8 Ma and 149.2 ±0.7 Ma (million years ago). The Kimmeridgian follows the Oxfordian and precedes the Tithonian.

Stratigraphic definition The Kimmeridgian Stage takes its name from the village of Kimmeridge on the Dorset coast, England. The name was introduced into the literature by French geologist Alcide d'Orbigny in 1842, although it seems to have been first suggested by Thomas Webster in 1812. The Kimmeridge Clay Formation takes its name from the same type location (although this formation extends from the Kimmeridgian stage of the Upper Jurassic into the Lower Cretaceous). It is the source for about 95% of the petroleum in the North Sea. Historically, the term Kimmeridgian has been used in two different ways. The base of the interval is the same but the top was defined by British stratigraphers as the base of the Portlandian (sensu anglico) whereas in France the top was defined as the base of the Tithonian (sensu gallico). The differences have not yet been fully resolved; As of 2004 Tithonian is the uppermost stage of the Jurassic in the timescale of the ICS. The base of the Kimmeridgian is at the first appearance of ammonite species Pictonia baylei in the stratigraphic column. The Global Boundary Stratotype Section and Point (GSSP) for the base of the Kimmeridgian is the Flodigarry section at Staffin Bay on the Isle of Skye, Scotland, which was ratified in 2021. The boundary is defined by the first appearance of ammonites marking the boreal Bauhini Zone and the subboreal Baylei Zone. The top of the Kimmeridgian (the base of the Tithonian) is at the first appearance of ammonite species Hybonoticeras hybonotum. It also coincides with the top of magnetic anomaly M22An.

Subdivision The Kimmeridgian is sometimes subdivided into Upper and Lower substages. In the Tethys domain, the Kimmeridgian contains seven ammonite biozones:

zone of Hybonoticeras beckeri zone of Aulacostephanus eudoxus zone of Aspidoceras acanthicum zone of Crussoliceras divisum zone of Ataxioceras hypselocyclum zone of Sutneria platynota zone of Idoceras planula

References

Notes

Literature Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press. Thurmann, J.; 1832: Sur Les Soulèvemens Jurassiques Du Porrentruy: Description Géognostique de la Série Jurassique et Théorie Orographique du Soulèvement, Mémoires de la Société d'histoire naturelle de Strasbourg 1: pp 1–84, F. G. Levrault, Paris.(in French)

External links GeoWhen Database - Kimmeridgian Jurassic-Cretaceous timescale, at the website of the subcommission for stratigraphic information of the ICS Stratigraphic chart of the Upper Jurassic, at the website of Norges Network of offshore records of geology and stratigraphy Howe, John Allen (1911). "Kimeridgian" . In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 15 (11th ed.). Cambridge University Press. pp. 799–800. This contains a detailed description of the layers (sensu anglico) and the fossiles found therein.

Worked examples

Example 1 — a first encounter with Kimmeridgian

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

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

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

Frequently asked questions

What is Kimmeridgian in simple terms?

Why does Kimmeridgian 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 Kimmeridgian?

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 Kimmeridgian.