406 Scientific Intelligence — Geology. 



on the shores of the Red Sea, in Tigre, Semen, Chire, &c. If we join 

 to this range of the geological scale, a great variety of sedimentary rocks, 

 rocks of plutonic and volcanic origin, also those usually named metamor- 

 phic, a considerable number of extinct volcanoes, hot springs, repositories 

 of iron, sulphur, rock-salt, combustible substances, malachite, &c., we 

 will obtain a general idea of the geological importance of Abyssinia. 



The general character of the relief of this country has been produced 

 by three kinds of ridges. The first is formed by the direction of the 

 mountains of Tarenta ; it affects the primary formations, and runs from 

 the north-west to south-east, that is to say, in a direction parallel with 

 the Arabian gulf. The second is represented by the mountains of the 

 transition formations of Tigre ; it evidently runs from the north-east to 

 south-west, that is, in a direction parallel to the shores of the Gulf of 

 Aden in the Indian Sea. Lastly, the third is formed by the general 

 direction of the tertiary plateaux of Tigre, Chile, Agame, &c. ; and runs 

 from north-north-west to south-south-east. 



It would be very interesting to connect the three systems of elevation 

 which MM. Galinier and Ferret have pointed out in Abyssinia, with the 

 general systems of elevation established by M. Elie de Beaumont ; but 

 for want of suiRcient data, the authors of the memoir have not attempted 

 to do this. With regard to volcanoes, MM. Galinier and Ferret have 

 observed, that the products of numerous volcanoes are to be seen in the 

 islands near Abyssinia, and on the shores of the sea. They consider it 

 probable that they existed before the period when the Ptolemies founded 

 establishments on the coasts ; but it is not certain that any now exist 

 in Abyssinia ; the springs of hot water they observed on the shore, could 

 not decide the question, although some reach 64° and 65°,* and even 

 exceed that. Many travellers, it is true, affirm that they have seen 

 volcanoes on the coasts of Choa. M. Rochet, in particular, has mentioned 

 the volcano of Dofano, and figured it as being in a state of activity ; it is 

 situate in the vicinity of Angobar ; but MM. Galinier and Ferret are of 

 opinion, that it is very possible M. Rochet has mistaken fumaroles for 

 a true volcanic eruption ; for the Abyssinians appear to have no idea of 

 volcanoes, t 



10. Limestone of Corfu and Vido. — Captain Portlock, R.E., is of 

 opinion that the limestone of Vido is probably oolite. 



11. Geology of Malta and Gozo. — From the observations of Lieut. 

 Spratt, R.N., it appears that the Maltese islands are formed of tertiary 

 strata, of the Middle or Miocene period. 



12. Rochs of Tangier. — In the travels of Badia, better known as Alt 

 Bey, occurs the following passage : — 



" The ground which forms the basis of the coast at Tangier, is com- 

 posed of different beds of secondary granite, of a compact or fine granu- 

 lar texture. These beds are inclined to the horizon, and form with it 

 a 1 angle of 50 to 70 degrees. They are generally one foot and a half 

 thick ; their direction runs from east to west, and their inclination, by 

 which the angle is formed, is northerly. 



" The distance between the beds is commonly about two feet, and 



• It is not mentioned whether of Reaumur or the Centigrade, 

 t L'Institut, No. 647, p. 210. 



