THE ANCIENT CITY OF PETRA IS ERODING:

�Petra is all about water, both its productivity when harnessed and its power of devastation when left uncontrolled,� says Glenn Markoe, curator at the Cincinnati Art Museum. The city, which went by different names over the centuries, had �a really elaborate water management scheme that people are just understanding now,� Markoe says. However, the flash floods that created the site�s canyons millions of years ago are now threatening to destroy it, aggravated by the increasing number of humans who flock to see what remains of the ancient site.