Carbon dating chart
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 that cut across other layers are younger than the layers they cut through (principle of cross-cutting relationships).
The principle of superposition builds on the principle of original horizontality.
Relative dating puts geologic events in chronological order without requiring that a specific numerical age be assigned to each event.
These changes typically occur so slowly that they are barely detectable over the span of a human life, yet even at this instant, the Earth's surface is moving and changing.
As these changes have occurred, organisms have evolved, and remnants of some have been preserved as fossils.
A fossil can be studied to determine what kind of organism it represents, how the organism lived, and how it was preserved.
However, by itself a fossil has little meaning unless it is placed within some context.The layers of rock at the base of the canyon were deposited first, and are thus older than the layers of rock exposed at the top (principle of superposition).In the Grand Canyon, the layers of strata are nearly horizontal.Despite seeming like a relatively stable place, the Earth's surface has changed dramatically over the past 4.6 billion years.