- GeoRef, Copyright 2006, American Geological Institute.
A key to interpretation of these deposits is the delineation of stillstand units, shallowing-upwards bodies of sediment deposited at a particular stand of the sea. These units provide a basis for studying vertical and lateral trends and identifying tectonic deformation. Criteria for identifying subtidal facies include: 1) abundant Ostrea lurida in growth position; 2) inclined strata more than 2 m thick; 3) laterally persistent lag deposits; 4) laterally peristent thin layers of mud; 5) medium- to large-scale crossbedding; 6) directionally uniform crossbedding and ripple lamination; and 7) assemblages of predominantly concave-up shells and shell fragments. Criteria for recognizing intertidal deposits include:) root or rhyzome structures; 2) runoff channels; 3) regular lamination characteristic of supratidal deposits; 4) supratidal bluff breccia; and 5) upper accretionary bank deposits underlying tidal flat deposits which underlie supratidal deposits.--Modified journal abstract.