SPRINGFIELD, MISSOURI—A new study of seeds and spores taken from the interior of Monks Mound suggests that the ten-story earthwork, the largest structure at Cahokia, was built more quickly than had been previously thought. Timothy Schilling and Neal Lopinot of Missouri State University collected the soil samples when repairs were conducted on the 1,000-year-old earthworks in 2005. “We were hoping to understand the source for the sediments in the mound,” Schilling told Western Digs. They found that all of the seeds in the 22 samples, except for plants such as elderberry, which were used for food, were annual plants. This suggests that the borrow pits, where the soil was collected, were disturbed frequently. “If there was a substantial time lapse between the use of the borrow pits, we would have a different environmental profile—more well established perennials versus weedy annuals,” Shilling said. The seeds in the samples were also well preserved and unburned, suggesting that they had not been exposed on the surface for very long. Earlier researchers had concluded that it had taken some 250 years to build the mound, but Schilling thinks that a period of about 20 years is more likely. For more, go to "Mississippian Burning."