CATARACTS AND INUNDATIONS. 



impression of the foot ; it bore us without any tremulous motion 

 whatever, and several head of cattle were browsing on it in perfect 

 security. In the dry season, however, tire surface is much more 

 yielding, and must be in a state approaching to fluidity, as is shown 

 by pieces of recent wood and other substances being enveloped in 

 it. Even large branches of trees which were a foot above the level, 

 liad in some way become enveloped in the bituminous matter. The 

 interstices or chasms are very numerous, ramifying and joining in 

 every direction, and in the wet season, being filled with water, present 

 the only obstacle to walking over the surface : these cavities are 

 generally deep iti proportion t their width, some being only a few 

 inches in depth, others several feet, and many almost unfathomable: 

 the water in them is good, and uncontaminated by the pitch; the 

 people of the neighbourhood derive their supply from this source, 

 and refresh themselves fey bathing in it ; fish are caught in it, and 

 particularly a very good species of mullet. The arrangement of the 

 chasms is very singular: the sides, which of course are formed of 

 the pitch, are invariably shelving from the surface, so as nearly to 

 meet at the bottom, but then they bulge out towards each other 

 with a considerable degree of convexity. This may be supposed to 

 arise from the tendency in the pitch slowly to coalesce, whenever 

 softened by the intensity of the sun's rays. These crevices are known 

 occasionally to close up entirely, and we saw many marks or seams 

 from this cause. How these crevices originate it may not be so easy 

 to explain. One of our party suggested that the whole mass of 

 pitch might be supported by the water which made its way through 

 accidental rents; but in the solid state it is of greater specific gravity 

 than water, for several bits thrown into one of the pools immediately 

 sank *. The lake (I call it so, because I think the common name 

 appropriate enough) contains many islets covered with long grass 

 and shrubbs, which are the haunts of birds of the most exquisite 

 plumage, as the pools are of snipe and plover. Alligators are also 

 said to abound here ; but it was not our lot to encounter anv of 



* Pieces of asphaltum are, I believe, frequently found floating on the Dead 

 Sea in Palestine ; but this arises probably from the extraordinary specific gravity 

 of the waters of that lake, which Dr. Marcet found to be 1-211. Mr. Hatchett 

 states the specific gravity of ordinary asphaltum to vary from 1-023 to 1-165, 

 but in two varieties of that of Trinidad it was as great as 1*336 and 1*774. 



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