Photograph from eastern Pennsylvania showing floodplain deposits from three distinct stages of watershed land use (picture tape in centimeters). The lowest material (below 60 cm) is old fertile alluvium that has a thick plow layer from agriculture in the 19th century. On top of this is stratified industrial coal washings (20-60 cm) from the early 20th century that buried this once fertile farmland in industrial waste. The upper most sandy material (0-20 cm) is human transported material from the construction of a nearby road in the past decade. This one soil profile clearly shows the evidence of human impacts from agriculture, industrial coal mining, and more modern suburban construction over the past 300 years.