allochthonous - Refers to something formed elsewhere than its present location. alluvial fan - An alluvial fan is a triangular-shaped deposit of sediment at the point where a river emerges from a mountainous area and flows onto a more gently sloping plain.alluvium - Sediment of sorted or unconsolidated sand, gravel, and clay that has been deposited by flowing water.abyssal plain - The ocean floor offshore from the continental margin, usually very flat with a slight slope.accrete - To add terranes (small land masses or pieces of crust) to another, usually larger, land mass. age - A unit of geological time shorter than an epoch, usually lasting several million years.barchan - A crescent-shaped sand dune moving across a clean surface with its convex face upwind and its concave slip face downwind.bar-finger sand - An elongated lens of sand deposited during the growth of a distributary in a delta.
bar (stream) - An accumulation of sediment, usually sandy, which forms at the borders or in the channels of streams or offshore from a beach.
basalt - A fine-grained, dark, mafic igneous rock (~50% Si O) composed largely of plagioclase feldspar and pyroxene; rough volcanic equivalent of gabbro.