earth science

Norian

Norian 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 Norian rather than just read about it. In short: The Norian is a division of the Triassic Period. It has the rank of an age (geochronology) or stage (chronostratigraphy).

Key takeaways

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

Reference excerpt

The Norian is a division of the Triassic Period. It has the rank of an age (geochronology) or stage (chronostratigraphy). It lasted from 227.3 to 205.7 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.

Stratigraphic definitions

The Norian was named after the Noric Alps in Austria. The stage was introduced into scientific literature by Austrian geologist Edmund Mojsisovics von Mojsvar in 1869. The Norian Stage begins at the base of the ammonite biozones of Klamathites macrolobatus and Stikinoceras kerri, and at the base of the conodont biozones of Metapolygnathus communisti and Metapolygnathus primitius. A global reference profile for the base (a GSSP) had in 2009 not yet been appointed. The top of the Norian (the base of the Rhaetian) is at the first appearance of ammonite species Cochloceras amoenum. The base of the Rheatian is also close to the first appearance of conodont species Misikella spp. and Epigondolella mosheri and the radiolarid species Proparvicingula moniliformis. In the Tethys domain, the Norian Stage contains six ammonite biozones:

zone of Halorites macer zone of Himavatites hogarti zone of Cyrtopleurites bicrenatus zone of Juvavites magnus zone of Malayites paulckei zone of Guembelites jandianus

Subages The Norian is divided into three global subages or substages:

Lacian (lower Norian) Alaunian (middle Norian) Sevatian (upper Norian) Many older studies considered the Rhaetian to be the uppermost substage of the Norian, though it has subsequently been raised to its own stage. The Revueltian land-vertebrate faunachron (LVF) corresponds to part of the Norian (215–207 Ma), and it is probable that the Otischalkian and Adamanian LVFs (227–215 Ma) are also early-middle Norian in age.

Notable formations Calcare di Zorzino (Italy) Caturrita Formation (Rio Grande do Sul, Brazil) Chinle Formation (Arizona and New Mexico, USA) Cow Branch Formation (North Carolina and Virginia, USA) Dockum Group (Carnian – Norian) (Texas and New Mexico, USA) Dolomia di Forni (Italy) Ischigualasto Formation (Carnian – Norian) (Argentina) Los Colorados Formation (Argentina) Stubensandstein (Germany) Trossingen Formation (Norian – Rhaetian) (Switzerland and Germany)

References

Notes

Literature Brack, P.; Rieber, H.; Nicora, A. & Mundil, R.; 2005: The Global boundary Stratotype Section and Point (GSSP) of the Ladinian Stage (Middle Triassic) at Bagolino (Southern Alps, Northern Italy) and its implications for the Triassic time scale, Episodes 28(4), pp. 233–244. Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press. Kielan-Jaworowska, Z.; Cifelli, R. L.; Luo, Zhe-Xi; 2004: Mammals from the Age of Dinosaurs, Columbia University Press. Martz, J.W.; 2008: Lithostratigraphy, chemostratigraphy, and vertebrate biostratigraphy of the Dockum Group (Upper Triassic), of southern Garza County, West Texas, Doctoral Dissertation, Texas Tech.

External links GeoWhen Database - Norian Upper Triassic timescale, at the website of the subcommission for stratigraphic information of the ICS Norges Network of offshore records of geology and stratigraphy: Stratigraphic charts for the Triassic, [1] and [2]

Illustrations

Worked examples

Example 1 — a first encounter with Norian

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

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

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

Frequently asked questions

What is Norian in simple terms?

The Norian is a division of the Triassic Period. It has the rank of an age (geochronology) or stage (chronostratigraphy).

Why does Norian 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 Norian?

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 Norian.