3.2.1 Concepts of Stratigraphic subdivision and correlation 3.2.2 Methodology of Stratigraphic subdivision and correlation 3.3.1 Lithostratigraphic unit-LU 3.3.2 Biostratigraphic u.-BU 3.3.3 Chronostratigraphic u.-CU 3.3.4 Stratotype & GTS 3.3.5 Relations between stratal u. 3.4.1 vertical aggradation 3.4.2 Lateral aggradation 3.4.3 Biological sedimentation 3.4.4 海进与海退 Transgression & regression