Define radiometric age dating

Despite this, the "principle of cross cutting relationships" can be used to determine the sequence of deposition, folds, and faults based on their intersections -- if folds and faults deform or cut across the sedimentary layers and surfaces, then they obviously came after deposition of the sediments.

You can't deform a structure (e.g., bedding) that is not there yet!

The simplest situation for a geologist is a "layer cake" succession of sedimentary or extrusive igneous rock units arranged in nearly horizontal layers.

In such a situation, the "principle of superposition" is easily applied, and the strata towards the bottom are older, those towards the top are younger.

In order for a layer of material to be deposited, something has to be beneath it to support it.

An early summary of them is found in Charles Lyell's .

In no way are they meant to imply there are no exceptions.

Most of these principles were formally proposed by Nicolaus Steno (Niels Steensen, Danish), in 1669, although some have an even older heritage that extends as far back as the authors of the Bible.

A few principles were recognized and specified later.

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