Start Absolute dating relative dating

Absolute dating relative dating

However, note that because of the "principle of cross-cutting relationships", careful examination of the contact between the cave infill and the surrounding rock will reveal the true relative age relationships, as will the "principle of inclusion" if fragments of the surrounding rock are found within the infill.

The principle of superposition therefore has a clear implication for the age of a vertical succession of strata.

This document is partly based on a prior posting composed in reply to Ted Holden.

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

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.

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).

This orientation is not an assumption, because in virtually all situations, it is also possible to determine the original "way up" in the stratigraphic succession from "way up indicators".