SEPM Strata

shoreline

The demarcation line between paralic/deltaic and marine depositional setting as illustrated in the Figure below.

At the shore where clastic sedimentare depositional settings include beaches, estuaries or deltaic. The parasequences of the shore are identified by the vertical associations generated by tidal flats, deltas, and beaches. For instance the beach association shown below is applicable to the Clastic Outcrop Exercises that are focused on the shoreline expressed by high frequency clastic parasequences.

At a clastic beach shore the vertical section of sediment expresses Walther's Law ("Facies adjacent to one another in a continuous vertical sequence also accumulated adjacent to one another laterally"). This association is used in conjunction with stacking patterns of sediments and their associated sedimentary structures to interpret and so determine the depositional setting of the these clastic sediments. Similar associations are associated with the carbonate shoreline.

As indicated the figure above is applicable to the Clastic Outcrop Exercises on high frequency clastic parasequences. Note the hierarchy of sedimentary structures and their association, from seaward to landward, with the different depositional systems (after Coe et al, 2003) that are listed in Table 1 below.

a. Upper foreshore planar-cross bedded sandstone of wave swash zone overlying trough-cross stratified sandstone zone of breaking waves.
b. Burrowed sandstone of the middle shorface.
c. Offshore transition zone.
d. Upper foreshore planar-cross bedded sandstone of wave swash zone.
e. Upper shoreface sandstone of wave swash zone to offshore transition zone between storm wave base & fairweather base.

Setting

Relationship to Waves & Tide

sedimentary structures

coastal plain

tidal zone, subject to storm wash-over

trough-cross bedded fill of tidal inlet, estuarine & fluvial channels; rooted seat earths & coals

foreshore & upper shoreface

zone of breaking waves & the wave swash zone

trough-cross stratified sandstone sometimes overlain by planar-cross bedded sandstone

lower shoreface & delta-front sandstones

just above fair-weather wave base

current ripple beds
wave ripple beds,
hummocky cross-beds
contorted beds

transition between offshore shelf & lower shore-face

between storm wave-base & fair-weather wave-base

alternations of hummocky cross-stratified sandstone
highly burrowed silty mudstones

offshore shelf

below storm wave-base

highly burrowed mudstones

Table 1. The relationship of the sediments of the Blackhawk Formation to depositional setting, tide and waves, and sedimentary structures (after Coe et al, 2003 .