Graded beds form when a steep pile of sediment on the sea floor (or lake floor) suddenly slumps into a canyon or off a steep edge. As the sediment falls, water mixes in with it, creating a slurry of sediment and water that flows quickly down a sloping bottom. GRADED BEDDING means that the grain size within a bed decreases upwards. This type of bedding is commonly associated with so called turbidity currents. Sedimentary structures such as cross-beds, graded beds, and mud cracks are useful for determining which way was up in the original sequence of sediments.
REVERSED, or inverted, graded bedding, although recorded by several.