From: The Biblical Repository, Volume 4. Chapter “Notes on the Bedouins”, page 746. (Edward Robinson) Publisher, Gould and Newman, 1834. Original from, Harvard University.
http://books.google.ca/books?id=ceQZAAAAYAAJ&pg=PA746&lpg=PA746&dq=The+Biblical+Repository+Notes+on+the+bedouins+Edward+Robinson&source=bl&ots=KzH_cyG2WP&sig=nkGYdHPr3WDLA48qPQYh97uzMfw&hl=en&sa=X&ei=FlgOUsDJJeKs2wXyxoDYCA&ved=0CCoQ6AEwAA#v=onepage&q=The%20Biblical%20Repository%20Notes%20on%20the%20bedouins%20Edward%20Robinson&f=false

Bedouin nomads on desert plains had the ability to trace specific footsteps amid the crisscrossing of thousands of other footsteps. A shoeprint indicated a townsman whose camel likely carried valuables. These nomads could discern the mark of a barefoot townsman by its lighter imprint on the ground. The Bedouin preoccupation with footsteps was like reading a road map with a different understanding of landmarks.
“Many secret transactions are brought to light by this knowledge of the Athr or ‘footsteps’; and a Bedouin can scarcely hope to escape detection in any clandestine proceeding, as his passage is recorded upon the road in characters that every one of his Arabian neighbours can read.”

From: God Revealed: Your Image of Him Changes Everything, Grand Rapids, MI: Chosen Books, 2005 p. 65. (Graham Cooke)

“When a revived person walks through the desert, they leave water in their footsteps.”