1.Highstand Systems Tract(HST) which bottom is marked by the emergence of condensed sectionand top is a maximal flooding surfaceformed during the period from the ascent inflexion point(R)to the highest point(H) of lacustrine level change.
2.Transgressive Systems Tract(TST) which bottom is a first flooding surface and top is marked by the emergence of condensed section formed during the period from the lowest point(L) to the ascent inflexion point(R) of lacustrine level change.
