30 Notices of Memoirs — Dr. Hull — Geological Map of Egypt. 



The author refers to popular views held to explain the formation 

 of the ravine — earthquakes and fracture — and shows that these are 

 inadequate. The ravine has clearly been produced by erosion, of 

 which the marks are still visible on the sides ; the difficulty is to 

 explain how erosion could have produced a gorge of this kind with- 

 out weathering action and floods having denuded the sides. 



Above the gorge in Glen Glass was once a lake. This had been 

 silted up to the height of about 80 feet with sand, washed out of the 

 Glacial debris of the glen. When the barrier that confined the lake 

 gave way, the river flowed over the surface of the conglomerate, 

 carrying with it much sand from the lake silt, and using this as 

 a means of rapidly eroding the rock. When the chasm was deep 

 enough to prevent the floods from overflowing the banks, the sides 

 could not be widened to any great extent. The disproportion 

 between the deepening and widening process has been maintained, 

 thus causing the steep-sided narrow glen. The excavation now 

 going on is small, whilst the weather has some effect on the sides ; 

 so that ultimately there will be produced an ordinary valley. 



II. — Notice of an Outline Geological Map of Lower Egypt, 



Arabia Petelea, and Palestine. 



By Prof. Edward Hull, LL.D., F.B.S., F.G.S. 



THE map exhibited was enlarged from that which accompanies the 

 author's book " Mount Seir, Sinai, and Westei'n Palestine," 

 giving a narrative of the expedition sent out into these countries by 

 the Palestine Exploration Society in 1883-84. It embraces a region 

 extending from the valley of the Nile on the west to the table-land 

 of Edom (Mount Seir) and Moab, including the Jordan, Arabah 

 Valley, and the mountains of Sinai. Its northern limit is the Lebanon. 

 The following formations and divisions are represented : — 



f 1. Sandhills of Lower Egypt, the coast of Palestine, 

 and Arahah Valley. 



Eecent. -j 2. Alluvial Deposits of the Nile, the Ghor, and Jordan 



| Valley. 



L 3. Gravel of the "Wady el Arabah. 



f 1. Eaised Beaches bordering the Gulfs of Suez and 



-r, Akabah, the Isthmus of Suez, and borders of 



Eecent and | Palestine 



Post- Pliocene to < 2 _ ABcient resits of the Salt Sea (Dead Sea). 



Pliocene. | g 01d La ke-beds of the Sinaitic Peninsula and Arabah 



I Valley. 



!1. Upper Eocene. Calcareous Sandstone of Philistia. 



2. Middle and Lower Eocene. Nummulite Limestone. 



3. Upper Cretaceous. Cretaceous Limestone. 



4. Cenomanian. Nubian Sandstone. 



T ~ (1. Limestone of Wady Nasb. 



Lower Carboniferous. { 2 _ Desert Sandstoue a J nd Cong i oraer ate. 



Metamorphic Eocks j G it Gnd and varioug j^g f gchist> 



(Archaean ?). J ' ' 



Modern Volcanic ) ^^ Dolerit etc _ 



Bocks. j ' 



, r l Granite, Porphyry, Felstone, Diorite, etc. 

 Ancient Volcanic or Beds of Tuf | JJ Agglomerate of Wady Haroun and 



Plutonic Eocks. | Jebe i esh shomrahf 



