How does relative dating work

01-Oct-2016 06:12 by 4 Comments

How does relative dating work

However, the age of each fossil primate needs to be determined so that fossils of the same age found in different parts of the world and fossils of different ages can be compared.

Applying the principle of cross-cutting relationships, this fault that offsets the layers of rock must have occurred after the strata were deposited.

Third, magnetism in rocks can be used to estimate the age of a fossil site.

This method uses the orientation of the Earth's magnetic field, which has changed through time, to determine ages for fossils and rocks.

Layers of rock are deposited horizontally at the bottom of a lake (principle of original horizontality).

Younger layers are deposited on top of older layers (principle of superposition).

Geologists have established a set of principles that can be applied to sedimentary and volcanic rocks that are exposed at the Earth's surface to determine the relative ages of geological events preserved in the rock record.

For example, in the rocks exposed in the walls of the Grand Canyon (Figure 1) there are many horizontal layers, which are called strata.

Most sediment is either laid down horizontally in bodies of water like the oceans, or on land on the margins of streams and rivers.

Each time a new layer of sediment is deposited it is laid down horizontally on top of an older layer.

The principle states that any geologic features that cut across strata must have formed after the rocks they cut through (Figures 2 and 3).

According to the principle of original horizontality, these strata must have been deposited horizontally and then titled vertically after they were deposited.

The age of the fossil must be determined so it can be compared to other fossil species from the same time period.