4.3 Statistics of C. pulveratrix and M. yantaiensis in loess-paleosol
strata
In the Beiyao section, the maximum number of cold-aridiphilous snailsC. pulveratrix was 70, occurring at the depth of 9.7 m (belonging
to MIS6). In contrast, the maximum number of sub-humidiphilous snailsM. yantaiensis was 34, appearing at the depth of 4.5 m (belonging
to MIS3) (Figure 3). At the bottom of the interglacial paleosol S1, very
few of land snail fossils were left because of the influence of strong
pedogenesis. However, the other horizons in the section were rich in
snail fossils. Therefore, without considering this factor, the
cold-aridiphilous species C. pulveratrix had a certain number
distributing from MIS2 to MIS7, with two most abundant horizons (with
fossil number of 58 and 70) respectively in MIS4 and MIS6. The
sub-humidiphilous species M. yantaiensis were mainly found in
MIS3 and MIS7, with maximum number reaching up to 34 and 23,
respectively. Moreover, when the number of M. yantaiensisincreased in some horizon, the number of C. pulveratrix in the
same horizon or neigbouring horizons significantly reduced. Conversely,
when the number of C. pulveratrix reached the peak of the stage,
the number of M. yantaiensis approached the minimum or 0.