Since the beginning of the 20th century, loess biostratigraphy has been str
ongly influenced by investigations of mollusks, these shells constituting t
he major fossil remains found in loess sequences. The earlier studies mostl
y involved identifying species and determining biozones or assemblages with
regard to the presence or absence of key species, using the classic concep
t of biozones. Although this provided accurate elements with which to defin
e an indicative biostratigraphy, the time resolution was not always suffici
ently precise to connect those studies with the more recent and high resolu
tion analyses that are now routine in Quaternary investigations. This paper
reviews mollusk studies carried out in Northern Hemisphere loess sequences
and shows that a consideration of them. as both biostratigraphic and palae
oclimatic indices, enhances their potential and opens up particularly inter
esting areas of research. The first example demonstrates that the last glac
ial mollusk assemblages in North America show compositional similarities to
those in Europe. The climatic interpretation, however, appears more restri
cted by local conditions, The second example shows that climatic conditions
can be used to infer variations in the composition of biozones and, thus,
address the significance of the distributional pattern of key species. The
third example demonstrates the value of high-resolution studies and the pot
ential of comparing the results of mollusk analyses with other proxies as a
n underpinning of the biological interpretation. Finally, the need for more
high-resolution investigations in both North America and Asia is stressed.
(C) 2001 Elsevier Science B.V. All rights reserved.