EFFIGY MOUNDS NATIONAL MONUMENT

area of 1,475 ac (597 ha) containing numerous ancient Indian burial mounds, in northeastern Iowa, U.S., on the Mississippi River, a few miles north of McGregor. Established in 1949 and located on bluffs overlooking the river, the monument has 183 known mounds, some of which are in the shape of birds and bears. One mound has been dated as being about 2,500 years old, but the effigy mounds were built by a later culture (probably AD 5001300). Many of the mounds have yielded copper, bone, and stone tools of Indian origin. One of the bear mounds is 137 ft (42 m) long and 3.5 ft high.