The By-Passing and Discontinuous Deposition of Sedimentary Materials

Abstract

Features of the sediments in various basins observed indicate that more material was supplied to these basins than was finally deposited in them. Under this condition, sedimentation was locally restricted or interrupted at frequent intervals during which most or all of the material received was passed onward. Sedimentation of a sufficiency such that a temporary baselevel of deposition is attained at frequent intervals, is termed adequate. The view that most sedimentation in epeiric seas and on continental shelves has been closely controlled by a segregative, restrictive, and evening action under the influence of the profile of equilibrium, is supported. It is concluded that the profile of equilibrium controls sedimentation in the neritic environment through the agencies of by-passing and discontinuous deposition, and that an understanding of these agencies is a key to many problems in texture, stratification, lenticularity, and differing thicknesses of sediment at equivalent time horizons. It is further concluded that, where conditions of past adequate sedimentation were present during the laying down of a conformable succession, the absolute and comparative subsidence at a locality can be approximated within permissib e error, and various relations between coarse and fine-textured sediment can be explained.