"circa 1850: Three carved effigy pipes left by the Mound Builders or Hopewell of Ohio, an early pre-Columbian culture of Native Americans. (Photo by MPI/Getty Images)" -- Image Date: 1/1/1850 -- Image Date: 1/1/1850." (1850): Image Collection. EBSCO. Web. 26 Jan. 2011.

 

 

"The Great Serpent Mound in Adams County, Ohio, built by the Adena people between 800 BC and AD 400. This protected historical earthworks is nearly a quarter of a mile long and represents a giant snake holding an egg in its jaws. (Photo by MPI/Getty Images)" -- Image Date: 1/1/1888 -- Image Date: 1/1/1888." (1888): Image Collection. EBSCO. Web. 26 Jan. 2011.