Earth Science Chapter 11 Lesson 1 Key Concept Builder

Key Concept How was the geologic time scale developed?

Directions: On each line, write the term from the word bank that correctly completes each sentence. Each term
is used only once.

epochs	eras	fossils	Mesozoic
Paleozoic	Periods	Phanerozoic	Triassic

1.  Divisions in the geologic time scale
were developed based on differences
in the                                             
in different rock layers.

2.  Eons, the longest unit of geologic time,
are subdivided into
                                                 .

3.  Periods are subdivided into
                                                 .

4.  Jurassic and the Ordovician are examples
of geologic                                                   .

5.  The Cretaceous period is part of the
                                                 era.

6.  The Cambrian period is part of the
                                                 era.

7.  The Mesozoic era includes the
                                             period.

8.  The                                                eon
includes the Quaternary period.