Steno correctly explained how marine fossils could end up on mountains far from an ocean.

Fossils in a rock layer represent the organisms that lived when the rock was formed.

The oldest rock layers in the Grand Canyon are at the top.

A fault is always older than the rock layers it cuts through.

Nicholas Steno was the first scientist to question the Biblical age of Earth.

William Smith is often called the father of modern geology.

Rocks in different places that have the same index fossils are about the same age.

Microfossils are useful index fossils because they are so widespread.

The oldest ages are at the top of the geologic time scale.

Steno’s laws include the law of

The Colorado River must be younger than all of the rock layers through which it has eroded, according to the principle of

If you know the relative ages of two rocks, you know

In the 1600s, most Europeans believed that Earth was about

Eroded gaps in rock sequences are known as

The longest subdivisions of the geologic time scale are

The current epoch of the geologic time scale is the