“But how can you tell if it’s an Indian mound or just a hill,” my traveling companion asked as we walked through Pinson Mounds Archaeological State Park outside Jackson, Tenn. Good question. Earthworks, dramatic reminders of prehistoric people who used to live in North America, blend with their surroundings. These often pyramid-type structures, made of earth, over time, slump. Encroaching vegetation shrouds the mounds, which centuries ago would have been cleared of trees and shrubs; now, mounds almost disappear into the landscape, seeming to be naturally occurring rises rather than human-made ceremonial centers. That these mounds were made intentionally can be determined by the presence of “borrow pits,” where dirt was dug up to build up the mound, leading to strata of dissimilar dirt in mounds created by builders who deposited baskets of earth to create – slowly, slowly – the massive structures. Carbon-dating of buried bodies and artifacts in the mounds also indicates the age at which various materials were deposited. In the picture is North America’s largest Middle Woodlands mound (72 feet, but no doubt slumped since construction 200BC – 500AD). Understanding that there was once a vast civilization here that lasted perhaps thousands of years -- and is now gone -- is sobering. Looking upon this mound millennia ago, the builders, with names now lost to time, must have imagined this massive structure – and the powerful civilization that gave it birth – would last forever.