US Geological Survey
U.s. Geological Survey: Fossils, Rocks, and Time
Publication delves into the importance of studying the Earth's history and how we go about doing it. View pictures and diagrams showing the geological time scale and fossil succession.
Talk Origins Archive
Talk Origins Archive: Radiometric Dating and the Geological Time Scale
A lengthy article with lots of information about radiometric dating, including pictures and charts.
Other
Utah Geological Survey: How Do Geologists Know How Old a Rock Is?
Geologists generally know the age of a rock by determining the age of the group of rocks, or formation, that it is found in. The age of formations is marked on a geologic calendar known as the geologic time scale. Development of the...
Other
Planetary Society: Relative and Absolute Ages in Histories of Earth and the Moon
A lengthy scholarly article that discusses the geologic time scale, its history of development, age-dating events that occurred in different eras, and how absolute and relative dating are used to assess the ages of the Earth and Moon....
American Geosciences Institute
American Geosciences Institute: How Do Species Change Over Geologic Time?
Find out about the ways that species change and evolve over time and generations.
Open Curriculum
Open Curriculum: Studying the History of Life
This in-depth article illustrates the concept of geologic time, and helps the learner understand why fossils are rare.
American Geosciences Institute
American Geosciences Institute: What Can We Tell From the Fossil Record?
Find out what the fossil record tells scientists about the geologic and biological history of the Earth.