The Lowstand Systems Tract (LST) develops during and immediately after a relative fall in sea level, when the shoreline is displaced basinward to its lowest position. It is characterised by incised valley fills, basin floor fans, slope fans, and lowstand prograding wedges. It overlies the sequence boundary (unconformity on the shelf) and is overlain by the Transgressive Systems Tract (TST) as sea level rises again.