Age of Rocks

What is the scientific law that states in horizontal sedimentary rock, the oldest layers are at the bottom?

• intrusion

• fault

• index fossil

• superposition

What is the lava that hardens on or above the Earth's surface?

• intrusive igneous rock

• extrusive igneous rock

An igneous intrusion is always ___________ than the rock layers around it and beneath it.

• younger

• older

What do geologists call new rock layers that meet a much older rock surface beneath them?

• index fossil

• uncomformity

• superposition

• relative age

What is a rock's age compared with the ages of other rocks?

• absolute age

• relative age

What is the number of years since a rocked formed? The rock's ___________ .

• absolute age

• relative age

What are fossils that are widely distributed and represent an organism that exist briefly?

• cast

• preserved remains

• trace fossil

• index fossil

Geologist use _________ to determine the absolute age of rocks.

• absolute age dating

• relative age dating

• radiation dating

• radioactive dating

Geologist use the time it takes for a radioactive isotope to decay to half its original mass called a ___________ .

• radioactive decay

• isotope

• half-life

• carbon dating

How are sedimentary rocks formed?

• cooling and hardening
• heat and pressure
• compacting and cementing
• melting