1. Biostratigraphy Basis of Biostratigraphy Biozones Examples Problems
Magnetostratigraphy
Chemostratigraphy
Text: Manual, p. 31; Boggs, Ch. 17

2. Biostratigraphy
Biostratigraphy: divide and correlate rock packages using fossils.
* Boundaries may or may not correspond to lithostratigraphic boundaries.

3. Basis of Biostratigraphy
Faunal Succession
Systematic progression of fossils with time. Extinct fossils do not reappear in younger rocks.
The fifth tool that will help us determine the age relationships of rock layers in the Grand Canyon is a tool called Faunal Succession.
This principle recognizes that organisms evolve through time, When, a species goes extinct, it will never reappear again in younger rocks.
You can see on the chart above that there are established ranges in time during which different organisms like dinosaurs and humans have lived.
The important thing here is that there are predictable sequences of fossils that we will see as we look at a progression of older to younger rocks.
The patterns reproduce themselves in many places throughout the globe and are very useful to determining when a rock formed relative to other rocks.

4. Basis of Biostratigraphy
Evolution: all living things share a common history
Genetic Variation and Inheritance
Changing Environmental Conditions
Natural Selection
The fifth tool that will help us determine the age relationships of rock layers in the Grand Canyon is a tool called Faunal Succession.
This principle recognizes that organisms evolve through time, When, a species goes extinct, it will never reappear again in younger rocks.
You can see on the chart above that there are established ranges in time during which different organisms like dinosaurs and humans have lived.
The important thing here is that there are predictable sequences of fossils that we will see as we look at a progression of older to younger rocks.
The patterns reproduce themselves in many places throughout the globe and are very useful to determining when a rock formed relative to other rocks.
(Stanley, 1993)

5. Basis of Biostratigraphy
punctuated evolution
gradual evolution
rapid burst
small populations
geographic isolation
(after Gould, 1989)

6. Basis of Biostratigraphy

7. Basis of Biostratigraphy
Extinctions
Ordovician
Devonian
Permian
Triassic
Cretaceous
catastrophic events
local environmental change*

8. Biostratigraphy Methods Determine ranges of fossils in section
Divide into Biozones
Range: First to last occurrence of a taxon
Biozone: basic unit of biostratigraphy

9. index fossil: a fossil that is useful to determine biozones
Basis of Biostratigraphy
index fossil: a fossil that is useful to determine biozones
Characteristics of Good Index Fossils
abundant fossils
widespread distribution
lived for short period of time
readily preserved
clear identifcation

10. Basis of Biostratigraphy
Index Fossils

11. Basis of Biostratigraphy
conodonts
pollen
diatoms
foraminifera
radiolaria
In the Grand Canyon, some of the best indicators of relative ages in the rocks are the fossils that we can’t even see.
Microscopic fossils like the single-celled group of foraminifera are extremely valuable in assigning ages to many of the rock layers of the Grand Canyon.
As are the microscopic fossils called conodonts which are found widespread in rocks that formed in marine environments.
Because they are so widespread, and composed of the mineral apatite, they are believed to be the teeth of sea creatures that swam around the oceans losing quite a few teeth,
Conodonts and foraminfera and other plankton like radiolarians and even tiny grains of fossil pollen are widespread in rocks around the world and show a pattern of species evolution through time and are extremely valuable in determining relative ages of rocks in the Grand Canyon and around the world.
Index Fossils

12. Biostratigraphy Basis of Biostratigraphy Biozones Examples Problems
Magnetostratigraphy
Chemostratigraphy
Text: Manual, p. 31; Boggs, Ch. 17

13. Biozones Types of Biozones 1. Interval Zones 2. Assemblage Zones
3. Abundance Zones

14. Biozones Types of Biozones
1. Interval Zones – based on occurrences of 1 or 2 taxa.
Taxon Range Zone – FAD and LAD of one taxon
Concurrent Range Zone – overlap between: FAD Taxon 1 and LAD Taxon 2
Partial Range Zone – gap between: LAD Taxon 1 and FAD Taxon 2
Lineage Zone – FAD of Taxon 1 and FAD of Taxon 2
(a descendent)
Interzones – interval with no fossils

15. Biozones
Types of Interval Zones

16. Biozones Types of Biozones
Interval Zones – based on occurrences of 1 or 2 taxa.
Assemblage Zones – based on association of 3 or more taxa.

17. Biozones
Assemblage Zones

18. In this example, you see that in a sequence of rocks, you might find an assemblage of different fossils, some with shorter and some with longer periods of time in which they lived.
So we can you the presence of not just one, but a combination of different fossils to constrain the time period in which that rock layer formed.

19. Biozones Types of Biozones
Interval Zones – based on occurrences of 1 or 2 taxa.
Assemblage Zones – based on association of 3 or more taxa.
Abundance Zones – based on peak abundance of
one or more taxa.

20. Biozones
Abundance Zones
Not Necessarily Time Equivalent!

21. Biozones
Taxon Range Zone?
Concurrent Range Zone?
Assemblage Zone?

22. Biozones
Partial Range Zone?
Abundance Zone?
Lineage Zone?

23. Biostratigraphy Basis of Biostratigraphy Biozones Examples Problems
Magnetostratigraphy
Chemostratigraphy
Text: Manual, p. 31; Boggs, Ch. 17

24. principles of stratigraphy marker horizons geophysical properties
Examples
Correlation
index fossils
principles of stratigraphy
marker horizons
geophysical properties
geochemical properties

25. Examples
Multiple Zones

26. Examples
Sedimentation Rates

27. Biostratigraphy Basis of Biostratigraphy Biozones Examples Problems
Magnetostratigraphy
Chemostratigraphy
Text: Manual, p. 31; Boggs, Ch. 17

28. Problems Facies Control on Distribution Taphonomy
Collection and Identification Bias

29. Problems
Environmentally Restricted Distribution of Species

30. Biostratigraphy Basis of Biostratigraphy Biozones Examples Problems
Magnetostratigraphy
Chemostratigraphy
Text: Manual, p. 31; Boggs, Ch. 17

31. Magnetostratigraphy
Magnetostratigraphy: divide and correlate rock packages using magnetic properties of the rock.
(Stanley, 1989)
normal magnetic field – polarity like today
reversed magnetic field – polarity opposite of today

32. Magnetostratigraphy decrease in magnetic field strength reversal
increase in magnetic field strength
Remnant Magnetism
(Long, 2005)

33. Magnetostratigraphy

34. Magnetostratigraphy
Polarity Zone

35. Magnetostratigraphy
Correlation

36. Biostratigraphy Basis of Biostratigraphy Biozones Examples Problems
Magnetostratigraphy
Chemostratigraphy
Text: Manual, p. 31; Boggs, Ch. 17

37. Chemostratigraphy
Chemostratigraphy: divide and correlate rock packages using chemical properties of the rock.
Isotope

38. Chemostratigraphy

39. Chemostratigraphy

40. Chemostratigraphy Strontium Isotopes 87Rb  87Sr
Old Crust – High 87Sr/86Sr
Sr sources vary