Relative and Absolute Dating Review

Front

What does the Principle of Original Horizontality state?

Back

Layers of sediment are deposited in horizontal layers.

Front

What is the Law of Superposition?

Back

The older layers of rock are always on the bottom, and the newer, younger ones are on top.

Front

What is the half-life of Iodine-131?

Back

8 days.

Front

How much Iodine-131 is left after one half-life if the original sample was 40 grams?

Back

20 grams.

Front

What does the Principle of Unconformities describe?

Back

Gaps in the geologic record as characterized by erosion.

Front

What is the Principle of Inclusion?

Back

If another rock is inside a rock layer, it is 'included' and usually older than the layer it cut through.

Front

What is relative dating?

Back

A method of determining the age of rocks and fossils in relation to one another.

Front

What is absolute dating?

Back

A method of determining the exact age of a rock or fossil, often using radiometric techniques.

Front

What is a sedimentary layer?

Back

A layer of sediment that has been deposited over time, often forming rocks.

Front

What is an unconformity in geology?

Back

A surface that represents a gap in the geologic record, often due to erosion.