In this paper, the authors review recent
    progress in environmental magnetic studies of the red-clay sequence. Two
    contrasting formation mechanisms of hematite have been proposed. Classic
    viewpoints argue that the hematite forms by dehydrating ferrihydrites and thus
    high temperature and dry climate favor formation of hematite; whereas some
    authors propose that production of hematite results from aging of maghemite
    grains which are in turn produced by aging of ferrihydrites. In terms of
    paleoclimate implications, magnetic data suggest that during the Late Pliocene,
    the East Asian summer monsoon (EASM) was stronger than Early Pliocene periods.
    If future studies support this conclusion, then many proxies used to indicate
    the intensity of the EASM might be invalid.