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Hilt's law

Hilt's law 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 Hilt's law rather than just read about it. In short: Hilt's law is a geological law that states the deeper the coal, the higher its rank (grade). The law holds true if the thermal gradient is entirely vertical, but metamorphism may cause lateral changes of rank, irrespective of depth.

Key takeaways

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

Reference excerpt

Hilt's law is a geological law that states the deeper the coal, the higher its rank (grade). The law holds true if the thermal gradient is entirely vertical, but metamorphism may cause lateral changes of rank, irrespective of depth. Increasing depth of burial results in a decrease in the oxygen content of the coals. The phenomenon was observed by professor Carl Hilt (1873).

See also Coal assay

Bibliography Coal Geology by Larry Thomas, [1], # ISBN 0-471-48531-4, # ISBN 978-0-471-48531-5

Worked examples

Example 1 — a first encounter with Hilt's law

Start with the simplest possible case. Write down what Hilt's law 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 Hilt's law 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 Hilt's law 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 Hilt's law

In research
Hilt's law 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 Hilt's law 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
Hilt's law is common in secondary-school and first-year university syllabi. It links to neighbouring topics Coal, Geology stubs, so understanding it makes those chapters shorter.
In everyday life
Look for Hilt's law 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 Hilt's law in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Hilt's law means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Hilt's law out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Hilt's law in simple terms?

Hilt's law is a geological law that states the deeper the coal, the higher its rank (grade). The law holds true if the thermal gradient is entirely vertical, but metamorphism may cause lateral changes of rank, irrespective of depth.

Why does Hilt's law 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 Hilt's law?

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 Hilt's law.

Tags

  • Coal
  • Geology stubs

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