Fossils and Geological Time

Footprints and trails are examples of trace fossils

• true

• false

The law of superposition helps geologists determine the absolute age of a rock layer

• true

• false

Geologists divide Earth's long history into smaller units that make up the geologic time scale.

• true

• false

Fossils usually occur in metamorphic rock.

• true

• false

The relative age of a rock is:

• its age compared with the ages of other rocks

• less then the age of the fossils the rock contains

• the number of years since the rock formed

• its age based on how much carbon-14 the rock contains

What are fossils

• molds and casts of organisms that live today

• drawings of ancient animals and other organisms

• footprints or burrows of small animals that live today

• the preserved remains or traces of organisms that lived in the past

What has the study of fossils allowed scientists to do?

• describe past environments and the history of life

• study present ocean temperatures at different depths

• analyze the chemical composition of sedimentary rocks and minerals

• predict which organisms will become extinct in the future

The oldest rock layer in an undisturbed rock sequence occurs

• at the bottom of the sequence

• below the sedimentary rock layer

• below the unconformity

• at the top of the sequence

A fossil formed when minerals replace all or part of an organism is called a

• mold

• petrified fossil

• cast

• trace fossil

Special fossils that indicate to geologists the boundaries of geological time

• index fossils

• trace fossils

• mold fossils

• cast fossils