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Br. J. W. Gregory — Geology of Somali-land. 



the general geological structure of the countiy. The accompanying 

 section shows the topographical features, according to Capt. Swayne's 

 map and some notes given me by Mr. Aylnier. 



South of Berbera there is a low plain composed of recent marine 

 deposits, mostly covered by blown sand and soil. Eight miles 

 inland is the first of a series of east and west ridges which form 

 the " Maritime Mountains." These extend for about twelve miles. 

 Then follows the " Inland Plain," which is a continuation of the 

 coast plain : it ends abruptly at the height of 1800 feet, at the foot 

 of the north scarp of the Somali plateau. A steep track leads up 

 the face of this scai*p to the Sheikh Pass, at the height of 4000 feet, 

 which leads on to the plateau. East and west of the pass the north 

 edge of the plateau is much higher, rising at one point to G819 feet. 

 As a rule this northern edge is from 5000-5500 feet in height, 

 while a terrace a mile or two in breadth, known as Mirsa, runs 

 along its northern face at the height of about 4000 feet. The 

 northern edge of the plateau is jagged, and, seen from the north, 

 looks like a mountain range, and is therefore known as the Golis 

 Range. The whole of the low country to the north, consisting of 

 the Maritime Plain, Maritime Mountains, and Inland Plain, is 

 known to the Somalis as the " Guban." To the south of the Golis 

 the plateau descends gradually across the Haud to the valley of 

 the Webi Shebeyli. These topographical features may easily be 

 explained by the collections described. 



Haud 



TfanXime range 



Int<md plain 



Somali pJateau 



Alluvium. 



Limestone of Duba. 



VV - Bathonian Limestone, 

 [Bihin. 

 ///// Cherts and Limestones of the Golis. 



g|§ Bed and Purple Sandstones. |||||||| Archean Bocks. 



(The dotted line from Mirsa to the Haud is the level of the Sheikh Pass.) 



Section across Northern Somali-land. 



The Maritime and Inland Plains are both occupied by alluvium, 

 marine and subaerial. Through these rise three ridges. The first 

 two are formed of limestone. That at Bihin is unquestionably 

 Lower Oolitic, and no doubt Bathonian. That at Duba may be 

 a part of the same limestone, or a later one, possibly Xeocomian 

 in age. 



The highest and furthest inland of the three ridges consists of 

 Ai-chean gneisses, and is an outlier from the main Somali plateau. 



