Reports &, Proceedings — Geological Society of London. 287 



The structure was shown to be that of a tableland bisected by 

 a great rift-valley (Graben), and flacked by a coastal plain. 

 A section was exhibited illustrating East Jordanland acting as 

 a borst ; the boundary faults of the Jordan Trench ; the unequal 

 sinking of the contained blocks; the western section of the tableland 

 sunken with relation to the eastern, and thrown into an asymmetric 

 anticline, the limbs of which rise in steps through monoclinal 

 flexures or faults. 



Lantern-slides were used to illustrate the character of the country 

 and outstanding features in its geology, more particularly the 

 following: the dependence of the topography upon geological 

 structure, slopes depending on the attitude of the rocks and elevation 

 npon the raising or depressing of fault-blocks or on lava-flows; 

 basins and sunken areas in the tableland ; the scarps bounding the 

 Jordan Trench, especially the western fault and fault-blocks in 

 the Trench or against its walls that hava not sunk equally with 

 others; the upturned block of Jebel-TJsdum which, with the Dead 

 Sea bottom and the block north of Jericho, indicates a median fault 

 between the boundary-faults ; the interbanding of the Jebel-Usdum 

 salt with sandstone and shales that resemble Nubian Sandstone ; 

 the unconformity of the Jebel-Usdum formation with the Jordan 

 lake-beds (Lisan formation) which, with the chemical composition 

 of the salt (lack of bromine, etc.), shows that it is not a Jordan 

 lake-deposit; high lake-terraces in the centre of the Trench, with 

 corresponding ones north of Tiberias and south in the Araba Yalley, 

 showing that the Jordan lake stood 1,400 feet above the present 

 Dead Sea, and that there has been no marked warping since their 

 formation; old gravel-filled canons of the Arnon and Terka Main 

 which prove that the level of the Dead Sea before Jordan-lake days 

 stood at about its present level, and that climatic conditions must 

 have been about the same, also that it did not long; precede the 

 Jordan lake ; the Lisan formation of the Jordan lake-beds, thin 

 layers of mechanical and chemical sediments veneered along the 

 Jordan river with fluviatile clays ; bad- land topography near the 

 wadis and in the Lisan formation ; narrow box canons of the wadis 

 in the Jordan Trench and the more open valleys above producing 

 a sort of " hanging valley ". 



In the main, Blanckenhorn's recent work was confirmed, in 

 particular the fault forming the western border of the Trench and 

 disturbances and sinking in the tableland ; but new points were 

 mentioned, such as the evidence of a median fault within the 

 Trench ; the sea-cliffs of Lisan and Jebel-Usdum ; the wave-cut 

 shelf and the salt of Jebel-Usdum ; the tilting of the Jebel-Usdum 

 block and its independence from and unconformity with the old 

 lacustrine beds ; lack of disturbance and of warping since their 

 deposition ; the age and former level of the Old Dead Sea and the 

 recent rise in the present sea, the latter indicating an increase in 

 moisture and not drier conditions as generally supposed. 



A vote of thanks was unanimously accorded to Major Brock for 

 his lecture. 



