Abstract The causes of areal and temporal variation in palynofloras extracted from sedimentary rocks are divided into major sources of variation and extraneous sources of variation. Major sources include: (1) Time; (2) Climate; (3) Plant succession; (4) Variations in local weather conditions; (5) Area dominated by species; (6) Distance transported; (7) Mode of transportation; (8) Intensity of transporting medium; (9) Characteristics of depositional basin; (10) Rate of deposition; (11) Differential flotation of miospore species; (12) Bacterial and fungal corrosion; (13) Action of bottom burrowing organisms; (14) Turbulance of depositional basin; (15) Presence of teratological forms; and (16) Recycling, stratigraphic leakage and reworking. Extraneous sources include: (1) Sample preparation; (2) Slide preparation; and (3) Operator error. These sources of variation can be measured indirectly by defining their operating level in the geological maze, and sampling accordingly. A least‐squares covariate analysis ...