Rock Hawk Effigy Mound is comprised of thousands of pieces of quartzite. While referred to as a hawk, scholars do not know what type of bird the original builders intended to portray. The mound is one of two such effigy mounds found east of the Mississippi River. Current archaeologists believe Woodland Indians built the site between 1,000 and 3,000 years ago. These Native Americans may have been part of the Adena or Hopewell cultures, or they may have represented a different group.