Seven sedimentary complexes and two cyclothems are differentiated in the "ore-bearing clays" from the Częstochowa area. The nature of deposits and microfauna evidence deposition in shallow-marine oxidizing environment and

oscillatory changes of depth. Total number of foraminiferid individuals is correlated neither with granulation nor CaC03 content of deposits. A small variability and high dominance are most strongly marked in the case of foraminiferid assemblages from three parts of the geological section and emphasize the two sedimentary cycles distinguished. The

reaction of foraminiferdis to environmental changes is delayed as the changes are first reflected by deposits and later by foraminiferid assemblages. The stratigraphic and ecological value of miliolids is confirmed.