Lab: Matching Rock Layers
Introduction: Correlation is the process of matching rocks of the same age at different locations. Outcrops separated by
hundreds of miles can be correlated by using similarities of rock type, rock thickness, rock color, and the presence of
fossils know as index fossils. Index fossils existed for a very short time (Example: only in the Devonian) but were
distributed over a large geographic area. Usually, these animals and plants are marine (ocean) organisms. Another way
of correlating is using volcanic ash markers which represent a single event which can be traced over a large area.
Objective: Student will be able to correlate outcrops from different localities and describe the processes involved in
correlation.
Procedure: Cut out and correlate the four outcrops. You will find several unconformities. Glue an example of each layer
in Procedure A column. Do likewise to the four outcrops containing index fossils. Glue an example of each in Procedure B
column.
Vocabulary:
Correlation___________________________________________________________________
Index fossil___________________________________________________________________
Unconformity_________________________________________________________________
Contact Metamorphism_________________________________________________________
Questions:
1. Explain why some layers are missing from some outcrops? ______________________
______________________________________________________________________
2. These gaps in the rock record are called _______________________.
3. List the three ways to correlate:
a. ___________________________________________________________________
b. ___________________________________________________________________
c. ___________________________________________________________________
4. List the two characteristics of an index fossil.
a. ___________________________________________________________________
b. ___________________________________________________________________
5. In outcrops A and B in procedure A, how do you know the basalt was molten?
______________________________________________________________________
Cutouts