This document provides an explanation of the factors that are thought to drive the growth and retreat of continental glaciers which spread across the Earth during four periods of geologic history. These factors are thought ot be related to variations in Earth's orbit. Full description.

Through a higher-order integration of concepts and observations, students can combine information from several field labs, all discussed in the Starting Point collection, to construct an overall geologic history of the local region. This site details the learning goals, teaching notes and materials, method of assessment, and context of use of this lab. It also provides links to additional references ... Full description.

This Starting Point webpage describes a ConcepTest question that asks students to carefully examine the relative positions of lettered arrows on timeline and estimate the geologic ages represented by each arrow. Students must identify which letter corresponds most closely to the age of the oldest known rock on Earth. The website includes the question, typical student responses before and after discussion, ... Full description.

This activity asks students to place 6-10 events in Earth history on a timeline, first working in small groups and then as a class. Then, through questions, important points such as how certain events are dated, where humanity fits in, and so forth, can be brought up. The Starting Point website builds a context for the exercise by detailing the learning goals, teaching notes and materials (downloadable), ... Full description.

This website is a well-illustrated description of Snowball Earth controversy. The description includes an introduction, background information, arguments for and against snowball earth, figures and tables, discussion and conclusions as well as references. This is a useful site for a comprehensive description of the Snowball Earth theory. Full description.

This website is Google's (TM) dynamic history of geology links page. The page is very up-to-date with a wide variety of useful links. Full description.

This is a history-of-geology course that includes a great deal of Earth history material. The course describes historical development of geology as a scientific discipline from ancient civilizations to the modern space age, the historical context and cultural basis of major geological theories regarding the origin of the Earth and processes that have influenced the Earth's development, the lives and ... Full description.

This is the webpage of an introductory Earth History course at the University of Michigan. The course focuses on basic geologic language and principles, earth materials, depositional environments, geologic time, plate tectonic and evolutionary theory. The website contains online study guides, lecture notes, homework, and useful links. Full description.

This Enchanted Learning website contains a very detailed and hyperlinked geologic time line. Precambrian to Quaternary Eons are broken into Eras, Periods and Epochs and pivotal events of the time are also highlighted. The timeline is nicely illustrated and appropriate for all ages. Users may also follow links to other parts of the Enchanted Learning Earth website. Full description.

This interactive geologic timeline is part of the site for Yosemite National park. Users can scroll across the geologic timeline and find out what was happening on Earth at that time. The site also includes a nicely illustrated geologic overview of the park, a virtual hike, quizzes, and a glossary and reference page. Full description.