GIZA, EGYPT—ZME Science reports that geochemist Alain Véron and geoarchaeologist Christophe Morhange of Aix-Marselle University and their colleagues detected evidence of metal contamination in the soils of what was once ancient Egypt’s Khufu Harbor. Construction materials were transported through the harbor, and the area was also home to a copper toolmaking industry. The researchers analyzed the soil samples with inductively coupled plasma-mass spectrometry (ICP-MS) to measure levels of copper, arsenic, aluminum, iron, and titanium. They determined through radiocarbon dating that the contamination began around 3265 B.C., during the Predynastic period. The amount of copper in the soil, in particular, was found to be five to six times the amount expected to occur naturally. “We found the oldest regional metal contamination ever recorded in the world,” Véron said. Contamination peaked around 2500 B.C., during the period of pyramid construction, and continued until about 1000 B.C., through a period of civil unrest as the Nile River dwindled and Khufu Harbor shrank. Véron explained that the need for metal tools likely increased as fertile Nile floodplains were exposed and farmed, as previously shown by analysis of ancient pollen grains. To read about the skilled workers who helped build the Great Pyramid, go to “Journeys of the Pyramid Builders.”