SHEFFIELD, ENGLAND—Although definitive evidence for the construction date of Sheffield Castle has long eluded archaeologists, a small patch of burnt ground has now helped unravel the mystery, according to a Miami Herald report. Researchers from Wessex Archaeology uncovered the deposit on the side of the motte, or artificial hill, where the original castle once stood. They believe that it was created when builders lit a fire during initial castle construction. With help from Museum of London Archaeology and the University of Bradford, the team relied on a cutting-edge method known as archaeomagnetic dating to date the fire and therefore the castle’s foundation. This technique analyzes shifts in the Earth’s magnetic field that are locked into materials when they were last heated to estimate the age of archaeological features. The results determined that Sheffield Castle was originally built between a.d. 896 and 1173, possibly more than a century earlier than previously thought. To read about excavations beneath one of Britain's most majestic castles, go to "Letter from England: Stronghold of the Kings in the North."
