Isotope dating information

25 Dec

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

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

As an example of how they are used, radiometric dates from geologically simple, fossiliferous Cretaceous rocks in western North America are compared to the geological time scale.

To get to that point, there is also a historical discussion and description of non-radiometric dating methods.

There are situations where it potentially fails -- for example, in cave deposits.

In this situation, the cave contents are younger than both the bedrock below the cave and the suspended roof above.

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My thanks to both him and other critics for motivating me.

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!

Much of the Earth's geology consists of successional layers of different rock types, piled one on top of another.

The most common rocks observed in this form are sedimentary rocks (derived from what were formerly sediments), and extrusive igneous rocks (e.g., lavas, volcanic ash, and other formerly molten rocks extruded onto the Earth's surface).