Then he examined layers of sediment in these deep cores, using a suite of techniques to calculate the age of the sand, other rocks, and organic matter in each layer. (uvm.edu)
And that makes environmental decision - making — such as setting allowable amounts of sediment in fish habitat and land use regulation — also difficult. (sciencedaily.com)
However, studies of sediment cores have shown that natural dust deposition has been in decline. (nextbigfuture.com)