Difference between absolute and relative dating geology
bankfull stage - The height of water in a stream that just corresponds to the level of the surrounding floodplain.
bar - A unit of pressure equal to 10 to the sixth dynes/square centimeter; approximately one atmosphere.
astrobleme - A circular erosional feature that has been ascribed to the impact of a meteorite or comet.
atmosphere (unit) - A unit of pressure equal to 101,325 newtons per square meter, or about 14.7 pounds per square inch.
Geological analysis relies mainly on chemistry, physics and mathematics. a'a' lava - basaltic lava characterized by a rough or rubbly surface composed of broken lava blocks called clinker.
A-horizon - The uppermost layer of a soil, containing organic material and leached minerals.
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.
autochthonous - Refers to something formed in its present location. backwash - The return flow of water down a beach after a wave has broken.
anorthosite - An igneous rock predominantly composed of plagioclase feldspar (90–100%), and a minimal mafic component (0–10%).
Anorthosites constitute the light-colored areas of the Moon's surface.
angle of repose - The steepest slope angle in which particular sediment will lie without cascading down.
angstrom - A length of 10 meter or one hundred millionth of a centimeter. angular unconformity - An unconformity in which the bedding planes of the rocks above and below are not parallel.
archean, archaean - An eon of geologic time extending from about 3800 to 2500 million years ago. The Archean eon is divided into four eras: Eoarchean, Paleoarchean, Mesoarchean, and Neoarchean.