 | This article needs additional citations for verification .(June 2025) |
| Part of a series on |
| Geology |
|---|
 |
In geology, a succession is a series of strata or rock units in chronological order. Rock successions can be seen in cross sections through rock, for example in a road cut or cliff. With sedimentary layers of rocks, newer units will be above older units, except in cases of inversion. This paradigm is also called faunal succession and fossil succession.
Contents
William Smith's "discovery that strata may be identified by the fossils they contain became known as the law of faunal succession." [1] As a general rule: [1]
fossil organisms succeed one another in a definite and recognizable order through geologic time as recorded in the rock record. Each geologic formation has a different record of life from that in the formations above it and below it. The principle of faunal succession allows determination of the relative age of rocks using their fossil content.
In this way, "succession became a unifying principle by which rock units are categorized and recognized widely." [1]
This "general principle called the Law of Fossil Succession: The kinds of animals and plants found as fossils change through time. When we find the same kinds of fossils in rocks from different places, we know that the rocks are the same age." [2]
There is a technical distinction between succession and sequence that is important to geologists: succession is any layers of rock in chronological order, while sequence is chronological and uninterrupted. [3]
