Relative dating and absolute dating of fossils
This method is based on the assumption (which nearly always holds true) that deeper layers of rock were deposited earlier in Earth's history, and thus are older than more shallow layers.The successive layers of rock represent successive intervals of time.When carbon-14 falls to Earth, it is absorbed by plants.These plants are eaten by animals who, in turn, are eaten by even larger animals.Absolute dates must agree with dates from other relative methods in order to be valid.The most widely used and accepted form of absolute dating is radioactive decay dating. Radioactive decay refers to the process in which a radioactive form of an element is converted into a nonradioactive product at a regular rate.
The time it takes for one-half of the carbon-14 to decay (a period called a half-life) is 5,730 years.The older the pottery, the brighter the light that will be emitted.Using thermoluminescence, pottery pieces as old as 100,000 years can be dated with precision. Known as dendrochronology (pronounced den-dro-crow-NOL-o-gee), tree-ring dating is based on the fact that trees produce one growth ring each year.By measuring the amount of original and transformed atoms in an object, scientists can determine the age of that object.Cosmic rays: Invisible, high-energy particles that constantly bombard Earth from all directions in space.