Figure 3. Changes in carbon and oxygen isotopes of C. pulveratrix and M. yantaiensis snails over the last two glacial-interglacial cycles, in comparison with median grain size (Md), magnetic susceptibility (SUS) and deep-sea δ18O curve. Stages partition, age data and δ18O value(standardized) of MIS were from Martinson (1987),Md data were from Tang et al. (2017), SUS data were from Du and Liu (2014),14C and OSL age data ware from Du et al.(2011).