earth science

Sinemurian

Sinemurian 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 Sinemurian rather than just read about it. In short: In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.5 ±0.3 Ma and 192.9 ±0.3 Ma (million years ago).

Key takeaways

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

Reference excerpt

In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.5 ±0.3 Ma and 192.9 ±0.3 Ma (million years ago). The Sinemurian is preceded by the Hettangian and is followed by the Pliensbachian. In Europe the Sinemurian age, together with the Hettangian age, saw the deposition of the lower Lias, in Great Britain known as the Blue Lias.

Stratigraphic definitions The Sinemurian Stage was defined and introduced into scientific literature by French palaeontologist Alcide d'Orbigny in 1842. It takes its name from the French town of Semur-en-Auxois, near Dijon. The calcareous soil formed from the Jurassic limestone of the region is in part responsible for the character of the classic Sancerre wines. The base of the Sinemurian Stage is at the first appearance of the ammonite genera Vermiceras and Metophioceras in the stratigraphic record. A global reference profile (GSSP or golden spike) for the Sinemurian Stage is located in a cliff north of the hamlet of East Quantoxhead, 6 kilometers (3.7 mi) east of Watchet, Somerset, England.

The top of the Sinemurian (the base of the Pliensbachian) is at the first appearances of the ammonite species Bifericeras donovani and ammonite genus Apoderoceras. The Sinemurian contains six ammonite biozones in the Tethys domain:

zone of Echioceras raricostatum zone of Oxynoticeras oxynotum zone of Asteroceras obtusum zone of Caenisites turneri zone of Arnioceras semicostatum zone of Arietites bucklandi

References

Sources Bloos, G. & Page, K.N.; 2001: Global Stratotype Section and Point for base of the Sinemurian Stage (Lower Jurassic), Episodes 25(1), pp. 22–28, PDF Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press. d´Orbigny, A.C.V.M.D.; 1842: Paléontologie française. 1. Terrains oolitiques ou jurassiques, Bertrand, Paris. (in French)

Illustrations

Worked examples

Example 1 — a first encounter with Sinemurian

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

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

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

Frequently asked questions

What is Sinemurian in simple terms?

In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.5 ±0.3 Ma and 192.9 ±0.3 Ma (million years ago).

Why does Sinemurian 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 Sinemurian?

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 Sinemurian.