Relative dating
From CreationWiki, the encyclopedia of creation science
Relative dating is a technique that uses the "relative" positions of layers and fossils to assign estimated dates to strata. Uniformitarian geologists began using the principles of stratigraphy to assign dates to the layers of the geological column fossils back in the late 1700s. Relative dating uses a combination of fossil studies and structural interpretation to draw conclusions about the geological history of an area.
The principles of relative dating for continuous stratigraphic sequences: (as put forth by scientists such as Nicolas Steno):
- Principle of original horizontality
- Principle of continuity
- Principle of superposition
- Principle of cross-cutting relationships
- Principle of inclusion
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Principle of Original Horizontality
- Main Article: Principle of original horizontality
When a stratum is formed, the lower surface and surfaces of its sides corresponded with the surfaces of the adjacent bodies. The upper surface was parallel to the horizon, as far as that is possible. With the exception of the lowest stratum, all the strata were contained in two parallel planes to the horizon and were at one time parallel to the horizon.
The problem here is that strata in ocean deposits are not always horizontal and rates of sedimentation are not uniform on a global scale. This is shown to be the case by both seismic records and sub-marine coring.
Principle of Lateral Continuity
- Main Article: Principle of continuity
Strata are formed from sediments in a fluid. Therefore, when any stratum forms it must be bordered on its sides by another solid body. Otherwise, the sediments will run around the earth. When the bare sides of strata are found, a uniformitarian geologist will look for its continuation or find some solid body that could have halted it.
The problem here is that it has never been confirmed, from either deposits or sedimentary rocks, that the same stratum goes all round the Earth. It is assumed but in Studies in Flood Geology there are maps of locations were the so called geologic ages are found, showing significant gaps.
Principle of Superposition
- Main Article: Principle of superposition
The principle of superposition states that layers of rock (strata) are arranged in a time sequence providing they have been unaltered since their formation. In other words, each layer or stratum is younger than the one beneath it or older than the one above it, so that the youngest stratum will be at the top of the sequence and the oldest at the bottom. This interpretation follows from the basic logic that a layer of sediment cannot accumulate unless there is already a substrate on which it can collect, and when the lower stratum forms, none of the strata above it existed.
Principle of Cross-cutting Relationships
- Main Article: Principle of cross-cutting relationships
Principle of inclusion
- Main Article: Principle of inclusion
Related References
Creationist References:
Secular References:
- Relative Time Scale by the U.S. Geological Survey
- Relative dating by Wikipedia
See Also
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