Once overlain by glaciers, the geology is marked by glacial moraines as well as alluvial deposits from the Delta and Tanana Rivers. Numerous mineral deposits are found in the vicinity of Delta Junction ranging from gold to molybdenum to coal. A prominent natural feature on the landscape is Donnelly Dome, located within the Donnelly Training Area of Fort Wainwright (formerly a part of nearby Fort Greely until 2001), to the south of Delta Junction. This dome was formed as a glacier coming from the Alaska Range split in two, carving away sides of a former mountain.