earth science

Sierra Madre Formation

Sierra Madre Formation 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 Sierra Madre Formation rather than just read about it. In short: The Sierra Madre Formation is a geologic formation in Chiapas state, southern Mexico. It consists of marine dolomites and limestones.

Key takeaways

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

Reference excerpt

The Sierra Madre Formation is a geologic formation in Chiapas state, southern Mexico. It consists of marine dolomites and limestones. The formation dates to the Middle Cretaceous, spanning from the Aptian of the Early to the Cenomanian of the Late Cretaceous. The dolomites, dolomitic breccias and limestones of the formation have been deposited in a lagoonal to estuarine environment and contain many fossil fish, flora and rudists, typical reef-building organisms of the Cretaceous. The formation rests on top of the Santiago and San Ricardo Formations, and is overlain by the Campanian to Maastrichtian Ocozocoautla Formation. The thickness of a composite section of the formation amounts to 2,590 metres (8,500 ft).

Description The Sierra Madre Formation was first formally described by Gutiérrez Gil in 1956, but previously reported by other authors (Böse, 1905; Ver Wiebe, 1925; Müllerried, 1936; Imlay, 1944). The formation was studied in more detail and subdivided in several members (Chubb, 1959; Sánchez-Montes de Oca, 1969; Zavala-Moreno, 1971; Castro-Mora et al., 1975; Michaud, 1987; Quezada-Muñetón, 1987). A composed thickness of 2,590 metres (8,500 ft) was suggested by Steele and Waite (1986) for the Sierra Madre Formation, subdivided into 21 lithofacies. The lowermost lithofacies corresponds to the stratigraphic level of El Espinal quarry, defined by Steele and Waite (1986) as dolomite and dolomitic breccia, located between 650 and 700 metres (2,130 and 2,300 ft) from the base of the formation, which rests conformably on top of the Late Jurassic to Early Cretaceous San Ricardo Formation. The top is covered unconformably by the Campanian to Maastrichtian Ocozocoautla Formation. The depositional environment is described as an environment with high oxygen concentration and high primary productivity with sporadic influence of strong waves and/or currents in a brackish marginal marine environment; shallow lagoon or estuary.

Fossil content The formation preserves fossil fish, flora and marine invertebrates dating back to the Cretaceous period, ranging from the Aptian of the Early Cretaceous to the Cenomanian of the Late Cretaceous. The fossils in El Espinal quarry were found in finely laminated orange clay layers interbedded with dolomitic limestone and interbedded with relatively thick layers of cream limestone that range from 5 to 10 centimetres (2.0 to 3.9 in), with some layers showing ripples, desiccation cracks, algal mats, and flat-pebble conglomerates. Similar fossils have been found in the Tlayúa Formation, of Albian age in Puebla, southern Mexico, as fishes, one odonate nymph and isopods.

Fish Fossils of Archaeochiapasa mardoqueoi and Pepemkay, a Cenomanian prehistoric ray-finned fish, were found in the formation. Other prehistoric fish fossils, found in quarries near the Municipality of Ocozocoautla de Espinosa, include Macrosemiids (Macrosemiocotzus species), Clupeomorphs (Triplomystus applegatei and Paraclupea-like species), and Alepisauriformes (Saurorhamphus and Enchodus species).

Rudists These rudists are reported from the formation:

Flora The following flora were found in the formation:

See also Cretaceous Mexico List of fossiliferous stratigraphic units in Mexico Cedar Mountain Formation, contemporaneous fossiliferous formation in eastern Utah Escucha Formation, contemporaneous fossiliferous formation in Spain Santana Group, contemporaneous fossiliferous group in northeastern Brazil containing the Lagerstätten Crato Formation Romualdo Formation Kem Kem Beds, contemporaneous fossiliferous formation in Morocco Burmese amber, contemporaneous paleoecology from Myanmar

References

Bibliography Alvarado Ortega, J.; Ovalles, E. Damián; Blanco Piñón, A. (2009), "The fossil fishes from the Sierra Madre Formation, Ocozocoautla, Chiapas, Southern Mexico", Palaeontologia Electronica, 12, retrieved 2020-03-16 Vega, F.J.; García Barrera, P.; Perrilliat, M. Carmen; Coutiño, M.A.; Mariño Pérez, R. (2006), "El Espinal, a new plattenkalk facies locality from the Lower Cretaceous Sierra Madre Formation, Chiapas, southeastern Mexico", Revista Mexicana de Ciencias Geológicas, 23: 323–333, retrieved 2020-03-16

Further reading P. García Barrera. 2006. Rudists of Mexico: Historical Aspects and Selected Areas of Research. in F. J. Vega, T. G. Nyborg et al., eds., Studies on Mexican Paleontology, Vol. 24 of Topics in Geobiology, Springer, Dordrecht, Netherlands 61-78

Worked examples

Example 1 — a first encounter with Sierra Madre Formation

Start with the simplest possible case. Write down what Sierra Madre Formation 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 Sierra Madre Formation 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 Sierra Madre Formation 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 Sierra Madre Formation

In research: Sierra Madre Formation 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 Sierra Madre Formation 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: Sierra Madre Formation is common in secondary-school and first-year university syllabi. It links to neighbouring topics Albian Stage, Aptian Stage, Cenomanian Stage, so understanding it makes those chapters shorter.
In everyday life: Look for Sierra Madre Formation 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 Sierra Madre Formation in 20 minutes

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

Frequently asked questions

What is Sierra Madre Formation in simple terms?

The Sierra Madre Formation is a geologic formation in Chiapas state, southern Mexico. It consists of marine dolomites and limestones.

Why does Sierra Madre Formation 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 Sierra Madre Formation?

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 Sierra Madre Formation.