2.3
inGeologic
Time
VOCABULARY
Index fossil:
a fossil
that, because its approx-
imate date is known,
allows scientists to
determine the age of
ACTIVITY ONE
T
WENTY
C
ENTURIES
RA T I ONA L E
Students have a difficult time comprehending how short the span of
human history is in relation to Earth’s geological history. This lesson
sets the stage for paleoseismology by providing a context in geological
time.
F OCU S QU E S T I ON S
If no earthquakes have been recorded in my area since it was settled,
does that mean earthquakes never happen here?
OB J E C T I V E S
Students will:
Students will compare the time period of their own lives and that of
human history to the age of the Earth and events in Earth’s history.
MA T E R I A L S
Q
Student copies of Master 2.3a, Centuries Worksheet
Q
Twelve 500-sheet reams (one case) of standard copier paper
Q
Student copies of Master 2.3b, Selected Events in Human History
Q
Student copies of Master 2.3c, Earth History Events
Q
Scissors
age of the rock in which it is
imbedded.
Radiometric dating:
the process of
using natural radioactivity to
determine the age of rocks.
Strata (s. stratum):
layers of rock or
other materials formed at different
periods in geologic time.
P ROC E DUR E
Teacher Preparation
1. Obtain 12 reams of standard-size paper and stack them on a desk
where they will be visible to all students. Unwrap only the top ream.
On each of the lower reams, cut a strip 7 to 10 cm wide from the side
of each wrapper so the paper shows through. The results should be a
column of exposed paper edges 11 reams high. Stack the unwrapped
twelfth ream neatly on top, and place a copy of the Centuries
Worksheet on top of the stack.
A G U
/
F E M A
67
S
E I S M I C
S
L E U T H S
