History of Earth

Front

What is the half-life of a radioactive substance?

Back

The half-life is the time required for half of the radioactive atoms in a sample to decay.

Front

If the half-life of a radioactive group of atoms is 100 years, how old is the rock if there have been two half-lives?

Back

200 years.

Front

What causes Earth's tectonic plates to move?

Back

Convection currents in the mantle.

Front

How many half-lives have passed if 25% of the original radioactive atoms remain?

Back

2 half-lives.

Front

What evidence did Wegener use to support the theory of continental drift?

Back

The shape of the continents, similar fossils found on separate continents, and tree fossils found in odd places.

Front

What is the composition of the nucleus of a carbon-14 atom?

Back

6 protons and 8 neutrons.

Front

Define tectonic plates.

Back

Tectonic plates are large sections of the Earth's lithosphere that move and interact with each other.

Front

What is continental drift?

Back

Continental drift is the theory that continents move across the Earth's surface over geological time.

Front

What is the significance of fossils in understanding Earth's history?

Back

Fossils provide evidence of past life and help scientists understand the evolution of species and changes in the environment.

Front

What role do convection currents play in geology?

Back

Convection currents in the mantle drive the movement of tectonic plates.