274 eepoet — 1884. 



' 3. A geological reconnaissance along the line of route through the 

 districts of Sinai, Akahah, and the Wady el Arabah, including the follow- 

 ing particulars : — 



* (a) Collections of fossils from the Wady Nasb limestone, in addition 

 to those already made by Mr. Bauerman and Colonel Sir C. W. Wilson. 

 These fossils (which are being examined by Professor Sollas) go to show 

 that this limestone is of carboniferous age : the Wady Nash limestone 

 was found to continue over a considerable region north of Mount 

 Sinai, and was again recognised amongst the mountains of Moab on the 

 east side of the Salt Sea in the Wady el Hessi. As this limestone rests 

 upon a red sandstone foundation, this latter may also be assumed to be of 

 the same geological age, and therefore cannot be the representative of the 

 " Nubian sandstone " of Russeger, which (as Professor Zittel has shown) 

 is of cretaceous age. I propose to call this formation, thei*efore, " the 

 Desert Sandstone." It forms with the limestone a strip along the borders 

 of the ancient rocks of palaeozoic or archasan age, and is about 400 feet in 

 average thickness : the base is generally a conglomerate. 



' (6) Above the Wady Nasb limestone is another sandstone formation, 

 of which a large portion of the Debet er Ramleh is formed. It is laid 

 open in the Wadies Zelegah, Biyar, &c, and along the mountains of Edom 

 and Moab. Out of this rock have been hewn the ancient temples, tombs, 

 and dwellings of Petra and the Wady Musa. It stretches along the 

 southern escarpment of the Tih plateau, and forms the base of the 

 limestone cliffs along the margin of the Wady el Arabah as far north 

 as Neo-eb es Salni. This sandstone formation is soft, red, or beautifully 

 variegated, and is in all probability of cretaceous age, and therefore the 

 true representative of the " Nubian sandstone " of Russeger. It will 

 thus be seen that there are two red sandstone formations, one below, the 

 other above the carboniferous limestone of the Wady Nash. 



' (c) The geological structure of the Wady el Arabah was examined 

 throughout a distance of 120 miles from south to north. That it has 

 been hollowed out along the line of a main fault, ranging from the eastern 

 shore of the Salt Sea to that of the Gulf of Akabah, was clearly deter- 

 mined ; and the position of the fault itself was made out and laid down 

 on the map ' in six or seven places, one being about ten miles north of 

 Akabah, another near the watershed, in which places the limestone of 

 the Tih (cretaceo-nummulitic) is faulted against the old porphyritic and 

 metamorphic rocks. I give on the next page two sketch sections to illus- 

 trate the structure at these points. 



' There are numerous parallel and branching faults along the Arabah 

 Valley, but there is one leading fracture running along the base of the 

 Edomite mountains, to which the others are of secondary importance ; 

 this may be called " the Great Jordan Valley fault." The relations of 

 the rocks in the Ghor and Jordan Valley have already been shown by 

 Lartet, Tristram, Wilson, and others, to indicate the presence of a large 

 fault corresponding with the line of this remarkable depression, and the 

 author considers the fracture he has observed in the Arabah Valley to be 

 continuous with that of the Jordan. 



' (d) The ancient rocks which form the floor either of the Desert or 

 Nubian sandstone formations consist of granite, gneiss, porphyries, and 

 more rarely metamorphic schistose rocks — together with volcanic rocks, 



1 The map used was an enlarged plan from Smith and Grove's Ancient Atlas 

 (J. Murray). 



