This photo taken Tuesday, Oct. 23, 2012 and released by the National Geographic Society on Thursday, Jan. 10, 2013, shows a series of cairns left by people crossing the desert flats, to

 

              This photo taken Tuesday, Oct. 23, 2012 and released by the National Geographic Society on Thursday, Jan. 10, 2013, shows a series of cairns left by people crossing the desert flats, to
This photo taken Tuesday, Oct. 23, 2012 and released by the National Geographic Society on Thursday, Jan. 10, 2013, shows a series of cairns left by people crossing the desert flats, to help others navigate during dust storms, in Djibouti. Two-time Pulitzer Prize-winning reporter Paul Salopek has taken the first steps of an unimaginably long walk - a 21,000-mile (34,000-kilometer) journey from Ethiopia to Argentina expected to last seven years. (AP Photo/National Geographic, Paul Salopek) NO SALES, ONE TIME USE ONLY, NO ARCHIVE
Tags: Argentina