As part of an updated series of activity oriented educational materials dealing with aspects of the Guam environment, this publication focuses on the physical environment of Guam through an introduction to the geology of Guam. Contents include the formation of Guam, weathering and erosion, earthquakes, soil, and water. Activities investigate different rock types and their characteristics, geological history of Guam, weathering and erosion, earthquakes, schoolyard soils, and water resources. Activities are aimed at junior and senior high school students. (MR)