Date post: | 17-Dec-2015 |
Category: |
Documents |
Upload: | howard-small |
View: | 227 times |
Download: | 3 times |
Bio-Events
First appearances of new species First appearances of new higher taxa Extinctions of species Mass extinctions of multiple taxa Bio-events are unique points in geologic
time
Index Fossils
Some fossils are more useful than others for relative age determinations
Fossils that are most useful are called INDEX FOSSILS
What factors would maximize a fossil’s usefulness?
Index Fossils
Limited Stratigraphic Range Widespread Geographic
Distribution Commonly Pelagic Or, tolerant of a wide variety of
environments (found in many facies)
Geologic Time Scale
Standard subdivisions of Earth’s history A “common language” by international
agreement Bio-Events are used to subdivide Geologic Time Stratotypes or “type examples” are designated
so comparisons can be standardized
Geologic Time Scale
A hierarchy of time units Eon
Era Period
Epoch Age
Boundaries are defined by bio-events
Eons
Phanerozoic – “obvious life” – 530 Ma to present Proterozoic – “prototypical life” – 2.5 Ga to 530 Ma Archean – “ancient” – circa 4.6 Ga to 2.5 Ga Archean and Proterozoic comprise nearly 90% of
Earth’s history!
Phanerozoic Eon
Cenozoic Era – “modern life” – 65 Ma to present Mesozoic Era – “middle life” – 248 Ma to 65 Ma Paleozoic Era – “ancient life” – 543 Ma to 248 Ma
Learn the following (in order from oldest to youngest):
3 Eons 3 Eras of the Phanerozoic All of the Periods of the Phanerozoic and the
Eras to which they belong “Picks” – numerical ages of the boundaries
between Eons and between Eras
Systems, Series, Stages Devonian System
Upper Devonian Series Famennian Frasnian
Middle Devonian Series Givetian Eifelian
Lower Devonian Emsian Pragian Lochkovian
Silurian System Upper Silurian Series
Přídolí Stage
Index Fossilsand the S-D Boundary
Graptolites * Conodonts * Chitinozoans * Trilobites Brachiopods Cephalopods