Malacostratigraphy of Late Glacial and Holocene in Poland

Struc ture and com po si tion of mol lus can as sem blages de pend on natu ral fac tors such as: cli mate, vege ta tion, char ac ter of back ground, en vi ron mental con di tions and, in ten sity of geo logi cal pro cesses as well as on the hu man im pact. Vistulian and Holo cene com mu ni ties of snails and bi valves ex actly re flect changes of habi tats. Se quences of these fauna can be used for bi os tra tigra phy and stra tigraphi cal sched ule. The old est part of the pre sented scheme cor re sponds with Last Pleni gla cial char ac ter ized by poor com mu ni ties with a high con tent of open coun try spe cies ac cept ing the arc tic and sub arc tic cli mate. Cli matic fluc tua tions dur ing the Late Gla cial caused a sub stan tial re com po si tion of as sem - blages. In colder phases com mu ni ties abound ing in open coun try spe cies of high eco logi cal tol er ance oc cur commonly. Fauna con nected with warmer stages usu ally con tains wood land spe cies. At the be gin ning of the Holo cene, a rapid warm ing was fol lowed by the ex pan sion of for ests. Shade- loving spe cies in creased in number, while cold tol erant snails gradu ally dis ap peared. The maxi mal ex pan sion of wood land snails is con nected with the At lan tic Phase. Dur ing the Up per Holo cene mol lus can com mu ni ties in di cate the prog ress of hu man im pact. The pro posal of mala costra tigraphi cal sub di vi sion pre sented be low can be cor re lated with simi lar schemes de fined in neigh bor ing coun tries. It sup ple ment paly no logi cal schemes or even can be used as main way to stra tigraphi cal re con struc tions.