1. Notes Science SPI 0807.5.5 Relative Age of Fossils
Tennessee SPI Objective:
Compare fossils found in sedimentary rock to determine their relative age.
Essential Question(s)
1) How is sedimentary rock formed?
2) What is the law of superposition?
3) How are fossils in sedimentary rock formed?
4) How is relative age determined?
Success Criteria
I can determine the relative
age of fossils in sedimentary rock.

2. What Are Fossils? Fossil Types:
Body- the actual organism or part of the organism (bones)
Trace- not a part of the organism, but evidence the organism existed (bite marks on a tree)
What Are Fossils?
Fossils are the preserved physical remains of deceased organisms that are at least 10,000 years old
NOTE: Most organisms DO NOT become fossils after death
NOTE: The formation of fossils is a RARE event
Video Clip 01
Link (1 min 50 sec): What is a fossil?

3. How are Fossils Formed?
Fossils form in a variety of ways. Amber, ice, tar pits, etc.
For this lesson we will focus on fossils in sedimentary rock, the most common type.
Video Clip 02
Link (2 min 10 sec-stop at 1:45): Fossils in Sedimentary Rock

4. Link (1 min 38 sec): Law of Superposition-Laundry Basket Analogy
Sedimentary Rock
Sediment refers to particles of dirt, rock, and debris suspended in liquid. Sedimentary rock is formed from this.
Law of Superposition
Bottom layers in rocks are the oldest. Top layers are the youngest
Video Clip 03
Link (1 min 38 sec): Law of Superposition-Laundry Basket Analogy

5. Sedimentary Process and Fossils
A) Erosion washes away particles of dirt and rock.
B) These particles accumulate somewhere else into layers.
C) Deceased organisms sometimes accumulate in these layers
D) Under certain rare conditions, these organisms become fossils
E) Over time layers pile up on top of pre-existing layers
Index Fossil- fossil used to date surrounding rock layers.
Link ( 1 min 51 sec): Sedimentary Rock Formation
Video Clip 04

6. Link ( 4 min 10 sec): Laws of Relative Dating
We can tell if one fossil is older than another based on which
layer we find it in. (Deeper layers-older. Shallow layers-younger)
Video Clip 05
Link ( 4 min 10 sec): Laws of Relative Dating
Example: See 3 layers below …Layer A, Layer B, and Layer C
Layer C is older than layer B.
So fossils in deeper layers are older than fossils above it.
Layer B is older than layer A.
Fossil 1 is older than fossil 2.
Fossil 3 is the youngest
Youngest 3
Layer A 2
Layer B
Oldest 1
Layer C

7. Relative Age of Fossils
SPI
Relative Age of Fossils
Questions
Science

10. Endoskeletons
Exoskeletons

11. Relative Age of Fossils
SPI
Relative Age of Fossils
Questions
Science

12. Exit Ticket What is a fossil? What is the law of superposition?
How are fossils in sedimentary rock formed?
How do we determine relative age of fossils?