Geologic Time Scale quiz

More questions about Geologic Time Scale

These visible examples show the question style. LearnClash turns the full topic into ranked duels and spaced repetition.

1. 1 Easy

   Which period did most of Jurassic Park's dinosaurs live in?

   Answer: Cretaceous

   Why: Tyrannosaurus, Velociraptor and Triceratops all lived in the Late Cretaceous, while the film's Brachiosaurus and Dilophosaurus are truly Jurassic.

2. 2 Medium

   Which eon lasted the longest?

   Answer: Proterozoic

   Why: Nearly 2 billion years long, it beats the runner-up, the Archean, by more than 400 million years.

3. 3 Hard

   Which period was officially added to the time scale in 2004?

   Answer: Ediacaran

   Why: Ratified in 2004, the Ediacaran is the first period named in 120 years, sitting right before the Cambrian.

4. 4 Easy

   What extinct sea animals lasted about 270 million years?

   Answer: Trilobites

   Why: The end-Permian extinction finished them off about 252 million years ago, wiping out about 81% of marine species.

5. 5 Medium

   Which rule says lower rock layers formed before upper ones?

   Answer: Superposition

   Why: The rule holds only for undisturbed layers: folding can tip a stack of rock right over, putting the oldest layers on top.

6. 6 Hard

   What rock unit corresponds to a geologic period?

   Answer: System

   Why: Periods measure intervals of time, while systems are the physical rock layers deposited during them.