Relative Dating Methods Flashcards
Name the 2 methods of dating to determine the age of the fossil/artefact.
- Relative dating
- Absolute dating
What can relative dating find?
Determine whether a sample is older or younger than another
It puts fossils in order of the age of their geological age of formation without knowing their actual age.
Compare relative and absolute dating.
R- less specific- qualitative
A- more specific- quantitative
R- less expensive, less time effective
A- more expensive, more time-effective
What rocks do relative dating work best?
Sedimentary rocks- it has layered arrangement of sediments
If igneous rock is present between layers, an absolute age for this rock can be calculated using a different method (potassium-argon dating)
What is stratigraphy?
study of layers of rock
2 processes involved in stratigraphy:
- Principle of Superposition
- Correlation of Rock Strata
What is the principle of superposition?
assumes that layers at the top are
younger than those beneath them
∴ any fossils found in the top layers are most likely to be younger than fossils found in the lower
How can distortion occur?
Distortion can occur in the Earth’s crust due to moving tectonic plates
Principle has to be applied cautiously → fossils/artefacts can be disturbed by human activity/animals
What is the Correlation of Rock Strata?
Matching rock layers from one area to another.
Allows for deductions in the succession and relative age of the fossils.
What are index fossils?
Correlation of rock strata can be aided with index fossils.
Are fossils of organisms that are widely distributed and only present for a short period
∴ rocks with similar fossils must be the same age
Give an example of index fossils.
Trilobites in the Paleozoic Era
Fossilised pollen grains → give information about the type of vegetation present when the rock layer was laid down.
