Earth's History - Fossil Record

Scientists determine the age of rocks and fossils using 2 different techniques. These techniques are called radioactive or absolute dating and _________________ dating.

Atoms are isotopes that have the same atomic ___________ but have different atomic masses.

The nuclei of some isotopes release particles or energy or both. What are these isotopes called?

The amount of time it takes for 1/2 of a sample of isotope to decay is called the ___________ life.

When an organism dies the amount of _____________ remains constant over time.

• Carbon-14
• Carbon-12

When an organism dies the amount of ________________ continues to decay.

• Carbon-14
• Carbon-12

Carbon dating ____________ be used to date fossils older than 75,000 years old.

• can
• cannot

When a fossil is dated by measuring the amount of an isotope remaining, it is known as ______________ dating.

When a fossil is dated by comparing its placement with that of fossils in other layers of rock, it is known as __________________ dating.

Can a specimen be too old for Carbon dating? If so, what age and why?

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