502 Prof. FE. Hull—The Jordan and Dead Sea. 
VII.—Norts on Mr. IJ. C. Russety’s Paper on THE JoRDAN-ARABAH 
AND THE Deap SEA. 
By Professor Epwarp Hutt, LL.D., F.R.S. 
HAVE been very much interested in reading Mr. Russell’s two 
communications published in the Gxotogican Magazine for 
August and September last. The analogy which he draws between 
the history of the Dead Sea valley and that of some of the lake 
valleys in the western part of North America is instructive as 
showing how similar physical features can be accounted for on 
similar principles of interpretation over all parts of the world. 
Mr. Russell very properly draws attention to the paper by his 
colleague Mr. G. K. Gilbert on ‘The Topographical Features of 
Lake Shores,” in which principles of interpretation of physical 
phenomena are laid down applicable to lakes both of America and 
the Jordan-Arabah valley. With some of Mr. Russell’s inferences 
regarding special epochs in the history of this valley I am very 
much disposed to agree; more particularly in reference to the mode 
of formation of the Salt Mountain, Jebel Usdum; or rather, of the 
salt-rock which forms the lower part of its mass. If this inter- 
pretation be correct, it removes the difficulty of understanding why 
the rock-salt is confined to one small corner of the lake, which, at 
the time the salt was in course of formation, was vastly more 
extensive than at present. 
The case of the arm of the Caspian known as Kara Bughaz, which 
Mr. Russell cites, seems remarkably apposite to that of the Southern 
bay of the Dead Sea; and I feel obliged to the author for his sugges- 
tion. In reference to Mr. Russell’s statement that ‘‘we ought to 
look for an unconformity between the upper and lower lake beds 
due to the erosion of the lower member,” J wish to take this oppor- 
tunity of referring again to the peculiar structure in the rock-salt 
near the northern end of Jebel Usdum, where the white laminated 
marls, forming the upper part of this plateau, are seen resting 
horizontally on a mass of rock-salt, having an oblique structure ; 
that is, traversed by planes sloping southwards at an angle of about 
20°-25°. J made a sketch of this part of the cliff in my note-book, 
but from inability, through lack of time, to examine into the 
phenomena with more care than can be done from horse-back, I 
thought it prudent not to refer to the matter in the Geological 
Memoir,’ further than to notice it. 
My special purpose in this communication is to offer some 
additional information to that already given on the question whether 
or not the Jordan-Arabah valley originally communicated with the 
ocean through the Gulf of Akabah. Mr. Russell is not satisfied with 
the information already before him regarding the nature of the 
watershed of the Arabah. I have, therefore, referred back to my 
1 «The Jordan-Arahab Depression and the Dead Sea,” Gzon. Mac. Aug. and 
Sept. 1888, pp. 337-244 and 387-3965. 
* Gilbert, Fifth Annual Report U.S. Geological Survey (1883-84). 
3 Memoir on the Physical Geology of Arabia-Petraea and Palestine, p. 84 (1886). _ 
