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Strata

From CreationWiki, the encyclopedia of creation science

(Redirected from Stratigraphy)

Sequence of sedimentary rock layers (strata) from Lake Mead.

Strata is the plural of the word "stratum". In geology, a stratum is a layer of sedimentary rock that generally has the same sediment throughout and normally has other layers above and below it. So to say "Earth's strata" is another way of saying "the many sedimentary rock layers that make up Earth's crust". Stratum generally means the same thing as "layer" or "level".

The characteristics of strata have led to several principles:

1 Principle of Original Horizontality
2 Principle of Lateral Continuity
3 Principle of Superposition
4 Discussion
5 Gallery
6 See Also

Principle of Original Horizontality

Main Article: Principle of original horizontality

Anticlinal strata folds in western Iran.

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 Grand Staircase is an immense sequence of sedimentary rock layers that stretch south from Bryce Canyon National Park through Zion National Park and into the Grand Canyon.

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.

Discussion

All these concepts form the basic assumptions of modern geology regarding the formation and history of rocks. But there are good scientific reasons for concluding that these assumptions are wrong.

The fact is that strata are formed by sediments in a fluid but the standard stratigraphic model seems to ignore the affect of the fluid on sediments. So the chronology resulting from this model does not take into account the fact that currents exist in present day oceans. The simple fact is that the standard stratigraphic model does not correspond with observational data from contemporary sedimentology.

Stratification is characterized by segregation of particles according to size in bedding plane partings, but the standard stratigraphic model interprets strata as a succession of sedimentary layers and so it is contrary to both observation and experimentation.