Stratigraphy lab
Strata
Maker.
Build the record. Change global sea level, move the basin up or down, and vary sediment supply. The shoreline responds to the balance between accommodation and sediment input.
Coast → shelf → basin
Time-stratigraphic log
Sea level
Sand
Fine sand
Silt
Mud
Hiatus / missing time
Erosion / unconformity
Relative sea level
Global sea level
Accommodation vs. sediment supply.
Global sea-level change and basin subsidence or uplift alter the space available for sediment. Sediment supply determines how quickly that space is filled. A rising global sea level does not automatically mean the shoreline retreats. Read the time-stratigraphic log for grain-size trends, stacking patterns, and missing time.
Watch the shoreline.
If accommodation grows faster than sediment fills it, the shoreline tends to retreat landward. If sediment supply outpaces accommodation, the shoreline can prograde seaward even while global sea level is rising.