Vojen Ložek, 1965. "Problems of Analysis of the Quaternary Nonmarine Molluscan Fauna in Europe", International Studies on the Quaternary: Papers Prepared on the Occasion of the VII Congress of the International Association for Quaternary Research Boulder, Colorado, 1965, H. E. Wright, Jr., David G. Frey
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The geologic importance of Quaternary nonmarine mollusks is often overlooked, although these mollusks can furnish valuable data when careful methods of study are employed. It is necessary to base the study of mollusks on numerous observations of the fauna, both recent and fossil, and to work with close co-operation among all the disciplines of Quaternary geology. Uniformly studied quantitative collections from profiles studied in detail provide a solid basis for the paleomalacological work, which must depend on critical comparative observations of the recent fauna.
The Quaternary was characterized by climatic fluctuations and resulting changes in natural habitat, especially vegetation. Ecologic mollusk groups may be identified to correspond to the phases of the climatic cycle: forest, steppe, indifferent, and marsh and aquatic groups. The results of detailed analyses can be presented on diagrams that show the proportions of species and of the ecological groups. This arrangement should be sufficiently generalized to eliminate local influences. A detailed knowledge of modern mollusk groups, combined with that of the sedimentary environment, provides a basis for reconstruction of past malacological associations that constitute the thanatocoenosis in question.
In calcareous regions mollusks are the most abundant Quaternary fossils. They are much more numerous than vertebrates, and they complement paleobotanical finds that are relatively rare in regions rich in mollusks. Vertebrates are more useful in stratigraphic correlation than mollusks, which, however, play a major role in environmental reconstruction and detailed stratigraphy. They therefore equal fossil plants in significance.
Several index mollusks occur in the early Pleistocene as well as in the Holocene. The change from cold to warm periods is expressed clearly in changes of the mollusk fauna. The steppe fauna of the cold periods, which is recognizable during the loess phases by certain species and associations, is replaced in the warm phases by a forest fauna, which in the interglacials of Central Europe included southern elements, later extinct (interglacial index types). The Postglacial is characterized by a mollusk succession that makes possible a detailed subdivision similar to that based on paleobotany.
Malacology has the advantage of abundant material that can be easily recovered and studied. Systematic studies of Quaternary mollusks are carried on today in only a few countries. If mollusks are more extensively studied and a corrélation is made with paleobotanical and vertebrate studies, then malacology will attain a very significant position in Quaternary geology.