The Critical Zone

What is Geology?


Geology is near and dear to my life since I am a geologist. I cannot count the number of times I have been asked whether or not I have been out on a "dig" recently or whether I dug up any arrowheads or pottery during my recent field excursions. Geology is not archaeology! For this reason, I want to be sure that you are exposed to some basic information about geology, including a definition. Be aware that geology is a science subdivided into numerous sub-disciplines and that numerous university geoscience departments around the world offer degrees ranging from two-year associate's degrees to the Ph.D. This lesson should be viewed as an introduction to only the very basics of geology!

Check this out . . .

A set of talks covering various topics within the Geosciences is available for free use in schools at Your Planet Earth.

The Pennsylvania Topographic and Geologic Survey provides online resources for teachers, including lesson plans, relating to the geology of Pennsylvania. Visit the site and follow the hyperlink "For Teachers" to "Lesson Plans." Other states may offer similar resources.

Reading assignment

Please visit and read the following sites to be certain that you understand the basics of the field of geology.

Once you have completed that reading, you should understand that geology is the study of Earth: the materials of which it is composed, the processes that created those materials, and the history of the planet.

Much of what geologists work on focuses on rocks, classified into three basic types: igneous, sedimentary, and metamorphic.

Please visit the "Geology" section of to learn more about rocks.

  • Follow the link to "Identify rocks"
  • Continue on to "About igneous rocks"
  • Follow the links through the descriptions of sedimentary and metamorphic rocks

You will be asked some questions related to these readings in the following activity.