How does the geologic time scale organize Earth's history?

What evidence did scientists mainly use to construct the geologic time scale during the 19th century?

Which order places the four divisions from smallest to largest?

Approximately how old is Earth?

Which group of eons makes up the Precambrian?

Use the chart's boundary ages, not the cell heights. Which eon lasted the longest?

During which eon did Earth first form through the accumulation of space debris?

Which group appeared first in Earth's history?

What does the name Phanerozoic mean?

Which era began earliest within the Phanerozoic Eon?

Which group dominated many land ecosystems during the Mesozoic?

Which extinction occurred at the boundary marked A?

In which period do we live today?

Which period belongs in the empty cell?

According to this chart, which period begins at the boundary marked A?

According to the chart, which epoch began immediately after the Paleocene ended?

Which period's name comes from the Latin word for chalk?

In many U.S. charts, which pair subdivides the Carboniferous?

Which new evidence would best refine the numerical age of a geologic boundary?

Which sequence follows these groups' first appearance, from earliest to latest?