TRIPOLY TO BENGAZI. 
129 
wards took the precaution of dismounting when we had occasion to 
cross any part which was considered to be dangerous. We found on 
examination that many hollow spaces of considerable depth and 
extent existed in various parts of the marsh ; and that the crust of 
salt and mud which covered them was sometimes no more than two 
inches, and an inch and a half, in thickness. 
These usually occurred in the most level parts, but as the crust 
was everywhere in appearance the same, there were no means of 
ascertaining where they existed, but by breaking the surface which 
concealed them. 
The water contained in these hollows w^as invariably salt, or very 
brackish ; it was usually clear, and was in some places deep : the 
depth of mud below the water must also have been sometimes con- 
siderable, and the vacant space contained between the outer surface 
of the marsh and the water was in various instances observed to be 
as much as twelve and fifteen feet in depth. We had no means of 
ascertaining the depth of the water in the hollow alluded to above ; 
but the space between its surface and that of the marsh appeared 
to be more than twelve feet, and, from the sound occasioned by 
the fall of the pieces into it, its depth could scarcely have been less 
than six or eight feet. In that part of the marsh which surrounds 
the Gusser el Jebha the nature of these pits is very apparent ; for 
the ground being unequal, and overgrown with reeds and brush- 
wood, no crust has been formed over them, and their dimensions are 
therefore easily ascertained. They are here very numerous, and it 
would be scarcely possible to escape fallin g into them after dark, as 
s 
