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Learn Geology

Read the rocks under your feet like pages of Earth history.

Free to start. Built from a single prompt. No credit card.

Geology is the science of the solid Earth: the minerals and rocks it is made of, the processes that build and destroy them, and the 4.5 billion year history recorded in their layers. A geologist looks at a road cut and reads a story of ancient seas, volcanoes or mountain building. The skills are learnable in a sensible order, starting with identifying minerals by their properties and ending with reading geologic maps. Learnr builds a personalized geology course from a single prompt and teaches it in short, interactive lessons.

How to learn Geology, step by step

Identify minerals by their physical properties. Test hardness on the Mohs scale using a fingernail, a copper coin, glass and a steel nail, and check streak on unglazed porcelain. Learn quartz, feldspar, micas, calcite, which fizzes in dilute acid, and the common iron oxides.
Read rock textures, not just colors. Coarse crystals mean slow cooling (granite) and fine ones mean fast cooling (basalt). Sort sedimentary rocks by grain size, from conglomerate to sandstone to shale, and spot foliation as slate turns to schist and gneiss.
Order events with stratigraphic principles. Apply superposition, original horizontality, cross-cutting relationships and faunal succession, and learn to spot unconformities. Practice on cross-section diagrams by listing every layer, fault and intrusion from oldest to youngest.
Learn deep time and how rocks are dated. Memorize the eons and the eras of the geologic time scale, then learn radiometric dating: after each half-life, half the parent isotope remains. Work a few calculations and see how index fossils give relative ages.
Understand structures and the forces behind them. Link tension to normal faults, compression to reverse and thrust faults and folds, and shear to strike-slip faults. Learn to read strike and dip symbols and anticlines and synclines on a geologic map.
Visit outcrops with a notebook and hand lens. Visit road cuts, quarries with permission or beach cliffs, staying clear of traffic and unstable faces. Wear eye protection if you use a rock hammer, respect collecting rules in parks, and review identifications with daily Learnr lessons.

What you'll learn

Identify common minerals by hardness, streak, luster and cleavage
Classify igneous, sedimentary and metamorphic rocks by texture and composition
Apply stratigraphic principles to put geologic events in order
Calculate rock ages from radioactive half-lives
Interpret faults, folds and strike and dip on a geologic map

What's inside your Geology course

A sample path Learnr builds for Geology. Your real course adapts to your goal and level.

1. Minerals and crystal structure
2. Igneous rocks and volcanism
3. Sedimentary rocks and ancient environments
4. Metamorphism and the rock cycle
5. Geologic time, stratigraphy and dating
6. Structural geology, plate tectonics and field mapping

How long does it take to learn Geology?

An introductory physical geology course takes about 3 to 4 months at 4 to 6 hours a week. Reliable rock and mineral identification only comes with repeated handling of real samples, so field trips and a reference collection add months of practice.

What you need before you start

None for an introduction. Basic chemistry, like elements and bonds, helps with minerals, and simple algebra is enough for radiometric dating calculations.

Common mistakes to avoid

Identifying minerals by color alone. Color varies widely within one mineral, so rely on hardness, streak, cleavage and luster instead.
Ignoring texture when naming rocks. Grain size and arrangement tell you how a rock formed, which matters more than its exact minerals at first.
Hammering or collecting without care. Wear safety glasses, get permission on private land and check rules before collecting in parks or protected areas.

How Learnr builds your course

Type your topic

Tell Learnr you want to learn Geology, or get as specific as you like.

Get a personalized course

Learnr instantly builds a full Geology course tailored to your goal and skill level.

Learn and level up

Move through bite-sized lessons and interactive practice, earning XP and keeping your streak.

Geology questions, answered

How do geologists know how old rocks are?

Relative age comes from rock layers and cross-cutting features. Absolute age comes from radiometric dating, which measures how much of a radioactive isotope has decayed at a known rate.

Do I need a rock hammer to learn geology?

No. A hand lens, a streak plate, a steel nail and a notebook cover most identification. A hammer and safety glasses help for fresh surfaces but are not essential.

How is geology different from Earth science?

Geology goes deeper into the solid Earth: minerals, rocks, structures and geologic history. Earth science surveys the whole planet, including weather, oceans and space.