EKU Spring Semester
David Head and Mike Newell
SED 545/745
Who Was Here First – Relative Dating and Rock Strata Activity
Concept:
History of Earth: Geologic Time, Rock Strata and Relative Dating
Description of Activity:
1. Students practice sequencing cards that represent different rock layers based on
alphabetical characters that each card contains.
2. Students practice sequencing cards that represent different rock layers based on fossil
pictures each card contains.
3. Students practice sequencing rock layer images based on fossil pictures they contain.
This activity was developed from an activity found at http://www.ucmp.berkeley.edu/fosrec/index.html
Kentucky Core Academic Standards:
Science-Middle Level
Students who demonstrate an understanding can:
08-ESS1-4. Construct a scientific explanation based on evidence from rock strata for
how geologic time scale is used to organize Earth’s 4.6 billion year old history
Disciplinary Core Idea:
ESS1.C: The History of Planet Earth – The geologic time scale interpreted from rock
strata provides a way to organize Earth’s history. Analyses of rock strata and the fossil record provide
only relative dates, not an absolute scale.
Management Suggestions:
Group varying ability levels
Materials:
Fossils Activity PowerPoint and Key to Fossils handout
Relative Dating handout
Stratigraphy PowerPoint
Card Set A
Card Set B
Stratigraphic Sections activity
Procedure:
Begin with Fossils Activity PowerPoint and discuss how paleontologists can determine when these
animals inhabited earth by recording their location in rock strata. Use the Fossils Activity PP to teach
the names of the particular fossils used in the subsequent activities. Pair learners so they can quiz each
other on the names of the fossils and assess them so they are able to identify fossils by name.
Introduce the concept of Relative dating by discussing the handout entitled Relative Dating. Important
terms are underlined and are discussed and assessed later in the Stratigraphy PowerPoint.
View the Stratigraphy PowerPoint and answer/discuss the questions at the end of the PowerPoint. This
information is a review of the information presented in the Relative Dating handout in a multimedia
format.
Introduce Card Set A. Spread the cards with the nonsense syllables on the table and determine the
correct sequence of the eight cards by comparing letters that are common to individual cards and
therefore overlap. The first card in the sequence has “Set A” in the lower left hand corner and
represents the bottom sequence. If the “T” and “C” represent fossils in the oldest rock layer, they are
the oldest fossils, or the first fossils formed in the past for this sequence of rock layers. The letters
should be: TC – CGA – AU – UBN – ON – BN – DN – OXD.
Introduce Card Set B. Spread the cards on the table and examine each card. The cards contain sketches
of fossils. Each card represents a particular rock layer with a collection of fossils that are found in the
particular rock stratum. All of the fossils represented would be found in sedimentary rocks of marine
origin.
The oldest rock layer is marked with the letter “M” in the lower left hand corner. Students should find a
rock layers that has at least one of the fossils found in the oldest rock layer. This rock layer would be
younger as indicated by the appearance of new fossils in the rock stratum. Keep in mind that extinction
is forever. Once an organism disappears from the sequence it cannot reappear later. Use this
information to sequence the cards in a vertical stack of fossils in rock strata. Arrange them from oldest
to youngest with the oldest layer on the bottom and youngest on top. The order should spell
ORGANISM.
Introduce the Stratigraphic Sections activity. Students will be given a stack of rock sections containing
fossils. The oldest rock layer contains a Brachiopod and Eurypterid. Students should find rock layers
that contain at least one of the fossils found in the oldest rock layer. This rock layer would be younger
as indicated by the appearance of new fossils in the rock stratum. Reinforce to students that extinction
is forever, once an organism disappears from the sequence it cannot reappear later. Use this
information to sequence the rock strata in a vertical stack. Arrange them from oldest to youngest with
the oldest layer on the bottom and youngest on top. There is more than one correct combination. At
this point, if students are progressing at a rate that would allow an introduction of an additional
concept, you may begin teaching that rock ages are as follows (oldest to youngest) Dolomite –
Limestone – Shale – Sandstone. This information will assist them in arranging the rock layers in the one
correct order.