Many ancient peoples, such as the Egyptians living along the Nile, depended on annual floods and alluvial deposits to replenish the soils they were farming.
Alluvial soils are usually nutrient-rich and good for agriculture.
Aerial Photography - The various techniques of taking photographs of natural or cultural features from the air, using balloons, airplanes, satellites, and other sources, in order to study the features in their entirety from a top-down (bird's eye) view.
Aerial Reconnaissance - The technique of searching for sites and features, both cultural and natural, from the air, often using aerial photography or the human eye.
AMS - Accelerator Mass Spectrometry is an absolute dating technique that measures the amount of carbon-14 in an organic object and provides a rough indication of its age. Anthropology - The study of human beings, including their behavior, biology, linguistics, and social and cultural variations.