Tectonics · Rocks · Time · Earthquakes
Earth, read closely.
Ten plain-English lessons across the breadth of geology. 150+ practice questions with explanations. Interactive Mohs hardness identifier, earthquake magnitude calculator, and rock-cycle simulator. Free, forever, for anyone curious about the planet you stand on.
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Quick Start
Where to begin.
Core Topics
Ten lessons cover the whole field.
History
Case studies.
Thinkers
Famous geologists.
Timeline
Key milestones in geology.
Numbers
Earth by the numbers.
Deep Dives
Concepts worth understanding.
FAQ
Common questions, plain answers.
Comparison
Rock types, side by side.
Reference
Major earthquakes and volcanic events.
Reference
The geologic time scale.
Debates
Open questions in geology.
Formulas
Core geology formulas.
Step by Step
Lessons that teach.
Ten core geology topics, each with worked examples and three quick practice questions. About 10 to 15 minutes per lesson. Tap any to start.
Targeted Practice
Drill the concepts.
Quick 10-question quizzes from the full question bank. Each question is explained whether you get it right or wrong.
Interactive Tools
Numbers you can play with.
Plug in real values. Mohs hardness, magnitude conversion, radiometric dating, rock-cycle exploration.