1) Mesozoic Era
2) Precambrian Time
3) Cenozoic Era
4) Paleozoic Era
1) b
2) d
3) a
4) c
What is a Period
A unit of geologic time that subdivides eras.
What is Geologic Time Scale
A record of the geologic events and the evolution of life forms as shown in the fossil records.
What is an Era
A long unit of time used to divide the time between Precambrian Time and the present.
TRUUE OR FALSE
The geologic time scale is a record of the GEOLOGIC EVENTS AND THE EVOLUTION OF LIFE FORMS as shown in the fossil record
TRUE
The first step in developing THE GEOLOGIC TIME SCALE was studying rock layers and index fossils worldwide.
TRUE
Scientists divided the time between Precambrian time and the present into FOUR units of time, or eras.
FALSE: Three
PERIODS are subdivided into units of geologic time called ERAS.
FALSE: Eras, Periods
Because the time span of Earth's past is so great, geologists use the __________ time scale to show Earth's history.
Geologic
Scientists chose where units of geologic time began and ended based on major changes in ___________ at certain times.
Life Forms
The long span of time that begins geologic time is _____________.
Precambrian Time
Geologists divided the time between Precambrian Time and the present into three long units of time called __________.
Eras
The Triassic Period, the Jurassic Period, and the Cretaceous Period occurred in the ___________ Era.
Mesozoic
__________ for many of the geologic periods come rom places around the world where geologists first described the rocks and fossils of that period.
Names
