- The principle of superposition states that in an undisturbed sequence of sedimentary rocks, each layer is older than the one above it and younger than the one below it. Therefore, in each outcrop, the oldest layer is at the bottom and the youngest is at the top.
- The principle of faunal succession states that fossil organisms succeed one another in a definite and determinable order, and therefore any time period can be recognized by its fossil content.
- By correlating the layers based on the unique fossils they contain, we can match layers across different outcrops that were deposited at the same time.
- Layer E (Outcrop I) contains a V-shaped fossil and is the oldest layer in its sequence. Layer K (Outcrop II) contains a similar V-shaped fossil and is the oldest in its sequence. Layer Q (Outcrop III) contains a similar V-shaped fossil and is the oldest in its sequence. These three layers are correlated as being the same age.
- Layer D (Outcrop I) contains a circular fossil with radiating lines. Layer J (Outcrop II) contains a similar circular fossil with radiating lines. Layer P (Outcrop III) contains a similar circular fossil with radiating lines. These three layers are correlated as being the same age.
- Layer C (Outcrop I) contains a fan-shaped fossil. Layer I (Outcrop II) contains a similar fan-shaped fossil. Layer O (Outcrop III) contains a similar fan-shaped fossil. These three layers are correlated as being the same age.
- Layer B (Outcrop I) is a plain layer with no distinctive fossil. Layer H (Outcrop II) is a plain layer with no distinctive fossil. Layer N (Outcrop III) is a plain layer with no distinctive fossil. These three layers are correlated as being the same age.
- Layer A (Outcrop I) contains a shell-like fossil. Layer G (Outcrop II) contains a similar shell-like fossil. Layer M (Outcrop III) contains a similar shell-like fossil. These three layers are correlated as being the same age.
- Layer F (Outcrop II) is the topmost layer and contains no fossil. Layer L (Outcrop III) is the topmost layer and contains no fossil. These two layers are correlated as being the same age.
- The complete chronological order from oldest to youngest is: E/K/Q, D/J/P, C/I/O, B/H/N, A/G/M, F/L.
Parent Tip: Review the logic above to help your child master the concept of index fossils worksheet.
