26 



DR. J. W. GREGORT ON THE GEOLOGY AND [Feb. I9OO, 



On the Geology and Fossil Corals and Echinids of Somaliland. 

 By J. W. Gregory, D.Sc, F.G.S. (Eead December 6th, 1899.) 



[Plates I & II.] 



Contents. 



I. Introduction 26 



II. The Archaean Series 28 



III. The Somaliland Limestones 29 



IV. The Fossil Corals of Somaliland , 30 



V. The Fossil Echinoidea of Somaliland 41 



VI. The Limestone Sequence and the Date of the Founder- 

 ing of the Aden Gulf 42 



Fi£. 1. 



10 . ■ ■-■;, 



G o 1 i 5> c 7~ Qedais * ,v n> (»■,=» m-% - ; 



Crttj' sou* Sheikh, 

 l/flicstonis 4543 , 



La* 1 * 



SKETCH-MAP 



OF A PORTION OF 



SOMALI LAND, 



by J. W. Gregory, 

 D.Sc, F.G.S. 



Approximate Scale-. 

 463 miles = 1 inch. 



/". 



p Plateau | J ^ **$?}? "Granite 



3099 «*>*£ 



Limestone 

 on Archaean Gneiss 



oBurao 

 Archsean 



Eyk 



c Faradayro 



Archsean 



45° LONG.E. 



■3ftf* 



Archsean 





C'""""""""^^™^«^ 



Kirrit 

 gypsum & shale 

 over the cherty 



limestone. 



'*?& 



Chert-hearing 

 limestones 

 on Archseani 



God la Yareho 



I. Introduction. 



British Somaliland consists of a high plateau, of which the 

 northern scarp is separated from the Gulf of Aden by a belt 

 of low hills and plains, known as the Guban. The southern 

 plateau consists of a vast "block of Archaean rocks, mainly gneiss 

 and amphibolites, with intrusive pegmatite-dykes, and it is 



