Here is one of the vents pinpointed by the Cassini team. This was the only one of the four that seemed obvious to me in appearance. There are boulders scattered throughout the area, but you have to note the larger accumulation of boulders here at the center of this image where one of the 4 vents were revealed. It is conceivable that larger chunks of material (as well as fine particles) could potentially have been spewed from these vents occasionally or perhaps thousands of years ago… or both.
See this and all the other located vents of Baghdad / Cairo Sulci and of Damascus Sulcus at the Cyclops Cassini Imaging site.