in an undisturbed sequence of sedimentary rocks

Working out Earth’s history depended on realizing some key principles of relative time.

The geologic time scale and basic outline of Earth’s history were worked out long before we had any scientific means of assigning numerical age units, like years, to events of Earth history. Explain the relationship between time units and corresponding rock units-chronostratigraphy versus lithostratigraphy.List the eons, eras, and periods of the geologic time scale and explain the purpose behind the divisions.Outline how natural selection takes place as a mechanism of evolution.Define a fossil and describe types of fossils preservation.Explain how sedimentary sequences can be dated using radioisotopes and other techniques.

Explain how scientists know the numeric age of the Earth and other events in Earth history.

Explain how carbon-14 forms in the atmosphere and how it is used in dating recent events.

Describe how radioisotopic dating is accomplished and list the four key isotopes used.

Define an isotope, and explain alpha decay, beta decay, and electron capture as mechanisms of radioactive decay.

Apply relative dating principles to a block diagram and interpret the sequence of geologic events.

Describe the five principles of stratigraphy.

Explain the difference between relative time and numeric time.

Perhaps no place on Earth better exemplifies the principles geologists use to determine the ages of rocks than Arizona’s Grand Canyon National Park.

In an undisturbed sequence of sedimentary rocks