Then something strange happened : the loess in the terraces wasn 't on top of crushed rock anymore - it was on top of very finely laminated clay-rich sediments .
That work also used a novel statistical approach ( known as the loess method ) to analyse data , but he points out that its conclusions now appear even more incorrect than rival studies done by un agencies .
These deposits look suspiciously like some kind of lake or backwater channel deposits , but they are several hundred meters above the current valley floor and underneath loess deposits in terraces .