I. C. Russell—The Jordan-Arabah and the Dead Sea. 3893 
of our presenting more than a suggestion of the arguments which 
might be advanced in this connection. 
From a study of the fishes of the Jordan drainage system, 
Giinther’ concluded that “The system of the Jordan presents so 
many African types that it has to be included in a description of the 
African region as well as the Huropeo-Asiatic.” A similar conclusion 
has been advanced by Tristram in his great work on the Fauna and 
Flora of Palestine. This evidence, so far as it goes, is certainly on 
the side of a former connection of the Jordan with other drainage 
systems. 
Besides the facts furnished by the fauna of the Jordan drainage 
system in reference to a former connection with other drainage 
areas, we have physical evidence bearing on the same question. 
The Jordan-Arabah depression receives tributaries from the east 
and west through deeply eroded stream channels, which were cut to 
their present depth before the occupation of the basin by the lake 
which deposited sediment over so large a portion of its area. ‘The 
fact that these tributary channels were cut before the existence of 
the lake, the sediments of which partly fill them, is in itself sufficient 
proof that the basin at one time had free drainage. ‘The present 
topography of the basin indicates that the ancient drainage was 
southward through the Gulf of Akabah, but other outlets to the sea 
may have existed at various times during the earlier portions of its 
history. One of these, it may be suggested, may have been situated 
at the Pass of Jezreel, at present the lowest point in the rim of the 
basin. It is possible also that a former outlet has been concealed 
beneath the recent overflows of basaltic lava near the Sea of Galilee. 
These are mere suggestions, however, and we know of no facts, 
either to prove or disprove them. 
The change from the conditions of free drainage to those now 
prevailing seems to imply orographic movements, which cut off the 
Dead Sea basin from communication with the ocean and admitted of 
the existence of an inclosed lake. 
Instead of the evaporation of a single lake in this basin, as has 
been assumed by certain authors, we should expect in scanning its 
records to find evidences of many fluctuations of water-level, and, 
consequently, marked changes in its fauna and flora, as well as great 
variation in the chemical composition of its waters. We should look 
especially for the records of two periods of humidity, separated by a 
time of extreme aridity, during which the lake waters were concen- 
trated and deposited salt and gypsum. Following the last high-water 
stage, we should as a working hypothesis, postulate orographic move- 
ments which increased the depth of the basin several hundred feet, 
thus lowering the surface of the lake; accompanying or succeeding 
this movement was a climatic oscillation which caused the lake to 
contract owing to a decrease in humidity and an increase in precipi- 
tation. 
1 Quoted by W. H. Hudleston on the Geology of Palestine, Proc. Geologists’ 
Assoc. vol. viii. p. 47. 
* London, 1864, p. xii. 
