OF SEVERAL PARTS OF WESTERN ASIA. 369 



covered in many places with layers of chalky limestone. This 

 fact seems to settle its place among the formations ; proving it 

 1o be connected with the cretaceous group. But if rock salt be 

 essentially a volcanic product, as we have strong reason to be- 

 lieve, its position among the sti'atified rocks shows only how 

 late it was protruded. The salt of Usdum, beneath the surface, 

 has a highly crystalline structure, and is even almost limpid ; as 

 No. 423 will show. For that specimen I am indebted to Dr. 

 Robinson ; and having subjected it to chemical examination, it 

 showed distinct traces of a sulphate, as well as of lime and mag- 

 nesia ; but I could not detect in it either bromine or iodine. The 

 above ingredients exist in it in about the same proportion as in 

 fossil rock salt generally, as I ascertained by comparative trials ; 

 and it may be regarded as a tolerably pure variety of salt. Along 

 the western shore of the sea are several brackish springs : indeed, 

 we know of but one of much size that is sv/eet, namely, that at 

 Ain Jidy. Fragments of sulphur and nifre have also been picked 

 up on the shore in various places. 



The waters of the Dead Sea are subject»to a considerable rise 

 and fall during the year. The rains of winter and the melted 

 snows of Anti-Lebanon produce a rise of several feet, while the 

 long-continued heat of summer, being very intense in so deep a 

 gulf, produces an abundant evaporation. Robinson and Smith 

 saw decided evidence, in the drift-wood lodged along the shore, 

 that the waters had been, during some part of the year, as many 

 as fifteen feet higher than when they visited them. This of 

 course produces a considerable difference in the size of the sea 

 at different times : particularly at the south end. The valley 

 extending southerly is for several miles very low : so that, in fact, a 

 rise of the waters a few feet causes them to extend southerly 

 several miles. That tract, when the waters have retired, appears 

 like the estuary of a river, when the tide has gone out. The 

 . south end of the sea is, also, rather shallow, and there is reason 

 to believe that a ford has existed, and perhaps does now exist, a 

 considerable distance northerly from the end, where a remarkable 

 peninsula extends more than half-way across it. 



The very peculiar character of the Dead Sea water has long 



