FILE - In this Nov. 21, 1996, file photo, tourists cast their shadows on the ancient Anasazi ruins of Chaco Canyon in N.M. Research suggests that the three biggest archaeological sites in the ... more 
FILE - In this Nov. 21, 1996, file photo, tourists cast their shadows on the ancient Anasazi ruins of Chaco Canyon in N.M. Research suggests that the three biggest archaeological sites in the Southwest--Chaco Canyon, Aztec Ruins and Casas Grandes represent three successive stages of the same political regime. Nearly 30 top archaeologists from universities and organizations around the nation called on the U.S. Interior Department on Tuesday, June 30, 2015, to protect the area surrounding Chaco Culture National Historical Park from oil and gas development. (AP Photo/Eric Draper, File) less 
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Associated Press | Photo By Eric Draper, File
Tue, Jun 30, 2015 4:33 PM EDT