I. O. Russell—The Jordan-Arabah and the Dead Sea. 389 
Origin of the Jordan-Arabah Depression. 
The observations of Hull, Lartet, Tristram, and others, have 
shown that this depression has been produced by a fault. In other 
words, it is due to a fracture in the rocks forming the adjacent table 
lands, accompanied by a subsidence of the strata on the west side of 
the fracture in relation to the broken edges of the corresponding 
beds on the east. The amount of this displacement is not accurately 
known, and no doubt varies at different portions of the fault line, 
but is certainly several thousand feet. Judging from the sections 
published by Hull, 5000 or 6000 feet would be a reasonable 
minimum estimate. This great fracture follows the base of the 
escarpment bordering the Jordan-Arabah depression on the east, 
and passes beneath the Dead Sea near its eastern shore. Its full 
linear extent is not known, but it has been traced by Hull and others 
for perhaps 150 miles. Its course is somewhat irregular, and 
numerous branches or secondary faults are connected with it, but its 
general bearing throughout its entire course is a few degrees east 
of north. The hade of the fault plane has not been definitely 
determined at any locality so far as we can ascertain, but is repre- 
sented in sections published by various geologists as dipping toward 
the thrown block at a high angle; that is, it is considered as a 
normal fault, in distinction from reversed faults, in which the hade 
is toward the upthrow. 
The strata composing the plateaux adjacent to the Dead Sea fault 
have been but little disturbed except in proximity to the line of 
fracture, and over large areas are nearly horizontal. The rocks 
forming these plateaux are Cretaceous limestones and sandstones, 
resting on rocks of the Carboniferous system, which in their turn 
are underlain by metamorphic strata perhaps of Archean age, 
together with igneous rocks of ancient but unknown date. Besides 
these older formations there are, especially in the neighbourhood of 
the Sea of Galilee, volcanic dykes and overflows of basaltic lava that 
are geologically recent. 
The formation of the Jordan-Arabah depression, although due to 
a violent fracturing of the earth’s crust, cannot be considered as 
having been formed suddenly at a single great catastrophe, but, 
judging from what we know of the formation of similar faults in 
other regions, must have been of slow growth, accompanied by many 
earthquakes, and may perhaps be still increasing its displacement. 
The numerous earth tremors felt in Palestine during the present 
century may possibly owe their origin to slight slips along this line 
of fracture. 
Lakes in the Dead Sea Basin. 
The lacustrine history of the Dead Sea basin began with the time 
when the fault to which it owes its origin had gained sufficient 
dimensions to interrupt the previous drainage of the region. This 
statement is made on the supposition, in the absence of evidence to 
the contrary, that the south-western part of Asia Minor was a land 
surface at the time the fault was initiated. 
