This succession was based primarily on a series of deposits and events not directly related to glacial and interglacial periods，rather than on the more usual modern method of studying biological remains found in interglacial beds themselves interstratified within glacial deposits.求这句话的分析，尤其是最后的“themselves”。杨鹏难句中，翻译的时候，说“而这些间冰层本身又在冰川沉积物发生间层化（interstratified）“，但是后面解释的时候又说指代的是”biological remains“。