Why did geologists develop the geologic time scale?
The time span of Earth's past is so great that words like century, decade, year, month, week, and day don't suffice
What is the geologic time scale?
A record of the geologic events and the evolution of life forms as shown in the fossil record
What information did scientists use to develop the geologic time scale?
Information from rock layers and index fossils
What era are we in?
The Cenozoic Era
What period are we in?
The Quaternary Period
What is the first division of geologic time called?
Precambrian Time
What are the three eras in order from oldest to newest?
Paleozoic, Mesozoic, Cenozoic
What are the three long units of time between Precambrian Time and the present called?
Eras
What are eras subdivided into?
Periods
Where do the names of many geologic periods come from?
Places where geologists first described the rocks and fossils of that period
