Because rocks and the sediments that derive from them shape the landscapes on which people live, the study of geology is an important part of archaeological research. Geology affects the quality of soils, the availability of water, and the ability of certain kinds of plants to grow.
Rocks and minerals also provide raw materials to meet basic human necessities, including shelter and tools. Identifying the geological materials used in building construction and artifact manufacture helps archaeologists understand ancient technologies and subsistence strategies.
Core, projectile point from BLM–Anasazi Heritage Center collections; Mark Montgomery, photographer
Finally, when "exotic" materials are found far from their place of origin—for example turquoise and obsidian at Pueblo sites in the Mesa Verde region—archaeologists can begin to reconstruct ancient trade patterns.
A Thousand-Year-Old Social Network Revealed is an Earthwatch report about ancient obsidian trade (note: several of the tested obsidian specimens were from the Dillard site, a Crow Canyon excavation site where Earthwatch volunteers conducted test excavations).