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Soil, rock fragments, and other materials put in place by humans and used to extend a side slope or a land surface for a roadway or building site, or to build up low-lying land, hold back water (e.g., dam), or fill in an enclosed space (e.g., mine workings). Synonymous with man-made fill, but distinguished from naturally occurring, sedimentary fill.


The longest geologic time unit, consisting of Eras and their subordinate time units, i.e., Periods and Epochs. Another use of the term is to denote one billion years.


The unit of geologic time into which a Period is divided.


The unit of geologic time intermediate between an Eon and a Period; e.g., the Paleozoic Era.


A long, more or less continuous cliff or relatively steep slope facing in one general direction, breaking the continuity of the land by separating two levels of gently sloping surfaces, that is produced by erosion or faulting (e.g., Blue Ridge Escarpment).


The process of water coming through the leaves of trees and then evaporating into the air.


The process of mechanical weathering of igneous and metamorphic rocks by which concentric scales, plates, or shells of variable thickness are successively spalled or stripped from the bare surface of a rock mass.