Page 235 - Laboratory Manual in Physical Geology

BIG IDEAS PRE-LAB VIDEO

Geologists use relative and absolute dating techniques to
infer the ages of geologic features and events in geologic
history. Relative age dating is the process of determining
what happened first, second, and so on, in relation to
other geologic features and events. Absolute age dating
is the process of determining when something formed
or happened in exact units of time such as days, months,
or years. The “geologic time scale” is a chart showing
the chronological sequence (relative ages) of named
rock units and cooresponding divisions of relative time
arranged next to a scale of absolute age in years.

FOCUS YOUR INQUIRY

|
THINK How can you tell relative age relationships
About It among the parts of geologic cross sections
exposed in outcrops?

ACTIVITY 8.1 Geologic Inquiry for Relative Age
Dating (p. 208 )
THINK How can geologic cross sections be interpreted
About It | to establish the relative ages of rock units,
contacts, and other geologic features?

ACTIVITY 8.2 Determining Sequence of Events in
Geologic Cross Sections (p. 208 )

THINK | How are fossils used to tell geologic time and
infer Earth’s history?
About It
L A B O R A T O R Y 8 ACTIVITY 8.3 Using Index Fossils to Date Rocks and
Events (p. 212 )

THINK
|
How do geologists determine the absolute age,
in years, of Earth materials and events?
About It
ACTIVITY 8.4 Absolute Dating of Rocks and Fossils (p. 214 )
Dating of Rocks, THINK | How are relative and absolute dating techniques
used to analyze outcrops and infer geologic history?
About It
Fossils, and ACTIVITY 8.5 Infer Geologic History from a New Mexico
Outcrop (p. 216 )
Geologic Events ACTIVITY 8.6 CSI (Canyon Scene Investigation)
Arizona (p. 216 )

C ONTRIBUTING A UTHORS
Jonathan Bushee • Northern Kentucky University
John K. Osmond • Florida State University
Raman J. Singh • Northern Kentucky University

Fossil ferns, 310 million years old, from the Pennsylvanian
(Carboniferous) System of rocks, Pottsville, Pennsylvania (x1).
(Richard M. Busch)
207