Word: sediments
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...bombs, gouging out a crater the size of Rhode Island and throwing so much pulverized real estate into the stratosphere that the sun is blocked for months and Earth goes into a worldwide deep freeze. If the comet hits an ocean, a pall of dust rises from underwarter sediment, and a tidal wave several thousand feet high races across the sea and hundreds of miles inland...
...Here's a fresh concern: lead spewed into the skies above Europe by ancient silver smelters as far back as 2,600 years ago. The toxic by-product has been discovered in lake sediment in Sweden; the lead traces could still cause poisoning...
...evidence for communal living was the fact that groups of nests were found in a single layer of sediment, implying that they were all built in the same year. Beyond that, the nests were spaced an average of 23 ft. apart -- about the size of an adult maiasaur. Birds often do the same thing, laying their eggs close enough together for maximum mutual protection, yet far enough apart so that they can move easily past their neighbors. Inside the nests, Horner found lots of tiny eggshell fragments. If the baby maiasaurs had simply hatched and wandered off to fend...
...report in Nature suggests that such thinking is a myth. British scientists studied the pattern of soil erosion in the Patzcuaro basin, an area of southwestern Mexico that was a center of pre-Hispanic civilization. Sediment samples from the lake revealed that erosion rates were at least as high before as after the Spaniards' arrival. In fact, erosion appears to have fallen off after the conquest. The conclusion: a return to traditional farming methods is no guarantee of a return to Eden...
These layers of sediment become pages in urban history, which, in large measure, is the history of civilization. The need to preserve foods and seeds at trading centers in ancient Mesopotamia and Anatolia focused human ingenuity on the problem of storage and led eventually to the development of armories, banks and libraries. Along a treacherous path paved with bloodshed and pestilence, cities evolved as the repositories of humanity's collective intelligence: the record of culture and science that enables a civilization to benefit from the lessons of the past...