Chapter 8

By: Jessica Arnold

Uniformitarianism

• The scientific principle that natural processes that operated in the past still operate the same way today.

• The uniformitarian slogan is, "the present is the key to the past.”

Relative vs. Absolute Age

• The age of a rock or an event as compared with some other rock or event is the relative age

• Absolute dating is the process of determining a specific date for an archaeological or palaeontological site or artifact.

Radiometric Dating

• Radiometric dating (often called radioactive dating) is a technique used to date materials, usually based on a comparison between the amount of a naturally occurring radioactive isotope and its decay products.

• See Uranium-238 Decay Series worksheet and the Radiometric Dating Lab.

Isotopes

• Isotopes are different types of atoms (nuclides) of the same chemical element, each having a different number of neutrons.

• If you change the number of neutrons/protons then you would get a different element

Half lives

• Half-life is the period of time, for a substance undergoing decay, to decrease by half. The name originally was used to describe a characteristic

• For example, after two half-lives, there will be one fourth the original sample, after three half-lives one eight the original sample, and so forth.

Carbon Dating Use( Carbon-14 dating)

• Carbon-14 dating is a way of determining the age of certain archeological artifacts of a biological origin up to about 50,000 years old. It is used in dating things such as bone, cloth, wood and plant fibers that were created in the relatively recent past by human activities.

The End