Science Struck
Science Struck: Different Branches of Geography
Learn about the many specializations in the field of geography within its two branches of physical and human geography.
CK-12 Foundation
Ck 12: Earth Science: Precambrian Continents and Plate Tectonics Study Guide
[Free Registration/Login may be required to access all resource tools.] Summarizes the key points about geological processes that took place during the Precambrian Era. Includes a few questions to check for understanding.