198 JOSEPH THOMSON 0:S THE GEOLOGY OF [^^J iSqQ^ 



which produced the mountain-chain are the same as those which 

 formed the plateau. 



Allusion has already been made to two districts where local 

 disturbances of the strata have occurred. Of these, the most 

 interesting is Jebel Hadid, or Iron Mountain. Here the massive 

 compact limestones are thrust up from their horizontal position, till 

 they stand on end, forming a narrow range nearly 20 miles long, 

 recalling in its jagged skyline the dorsal fin of a fish. The internal 

 force, however, which was sufiicient to form a mountain-range 

 2500 feet high was not expended in the effort, and assumed a 

 volcanic character in drilling a way for itself through the heart of 

 the mountains, forming a huge pit, now nearly filled with the fallen 

 debris. Springs, probably hot and charged with hydrated oxides 

 of iron, succeeded what was doubtless a primary explosion of steam, 

 and deposited their mineral burden among the shattered rocks and 

 volcanic ejectamenta. In process of time, these springs either dried 

 up or found exits in other parts of the district ; and within the 

 historic period the natives of the country have found it worth their 

 while to extract the ore left behind in the famous iron-mines, whicL 

 have been worked from time immemorial, though totally disused at 

 the present day. It is not improbable that there is some connexion 

 between the Hadid disturbance and the curious pits in the Tertiary 

 rocks near Saffi. (see p. 195), as also the hot springs on the Kaib, 

 close to Mogador : they are all situated along the same line. 



Over the greater part of this Cretaceous area no fossils are found. 

 This is specially the case in the province of Shiedma and the greater 

 part of Haha. In Mtuga, however, and in the mountainous district 

 of the Ida-Utanein, fossiliferous beds are numerous and wiU certainly 

 yield a valuable harvest to the palaeontologist who can devote some 

 time to their examination. Unfortunately I myself was unable to 

 do much collecting, as I was in a manner flying for my life when 

 I crossed the fossiliferous district and dared not increase the danger 

 which we ran, by wasting time or adding to our impedimenta. The 

 few fossils that I was able to pick up, however, included charac- 

 teristic Cretaceous forms. 



Y. The Atlas Mountaii^s. 



Turning now to the Atlas Mountains, the third section into which 

 I have divided Southern Morocco, it should be clearly understoo3p 

 that, in speaking generally of the Atlas, I include simply that section 

 of the range which came under my own observation : namely, from 

 Demnat to the western end. 



Stated briefly, the Atlas exhibits an approximate repetition of the 

 geology of the plateau. There is, first, a core or backbone of meta- 

 morphic rock, more or less disturbed by the intrusion of diorite, 

 porphyrite, and other igneous rocks, and rising to the highest 

 elevation of the range. Secondly, there is an enormous development 

 of the Lower Cretaceous Series, flanking the metamorphic rocks on 



