Three-dimensional exposures provided by quarrying of aggregate have been used to determine the geometry of genetic units within a sequence of outwash gravels. The genetic units represent lithofacies associations and are of three types. Association A is predominantly composed of gravelly lithofacies interpreted to have been deposited as sheets by laterally migrating bar complexes in the active channel belt of a low sinuosity river. Association B comprises thin, discontinuous sheets of sandy lithofacies interpreted to have been deposited from shallow flows as floodplain or bar top sediments. Association C consists of sands and fine gravels deposited as channel fills....