It is usually due to erosion of lack of deposition.
Delta is deposition beach is deposition canyon is erosion sea cave is erosion sand dune is deposition
what is deposition
unconformity (plural unconformities)(nonstandard) A lack of conformity.(geology) A gap in time in rock strata, where erosion occurs while deposition slows or stops.
deposition
deposition
deposition
Deposition
deposition
deposition
deposition
Deposition