464 APPENDIX H. 



tlie east, near the source of the river Tensift, on his homeward 

 journey, speaks of them as from 500 to 1,200 feet in- height, 

 consisting of micaceous schist and a schistose rook with veins 

 of quartz dipping 75°, with a strike north by east and south by 

 west. The strike may vary a little at different points, and, taking 

 Lieut. Washington's and my own observations together, would 

 average about north and south ; and it is worthy of note that 

 these apparently ancient rocks are nearly at right angles to 

 the strike of the rocks of the Atlas chain a few miles to the 

 south. 



The only other metamorphic rocks that came under our 

 notice were : — first, white marble or metamorphic limestone, 

 intercalated with the porphyrites at the summit of the ridge of 

 the Atlas south of Arround ; secondly, mica-schists, pierced by 

 red porphyry dykes, forming the mass of Djebel Tezah, a peak 

 11,000 feet in height, and fifteen mUes farther west, ascended 

 by Dr. Hooker and Mr. Ball after my return. It is possible 

 that the mica-schists may be a portion of the grey-shale series, 

 metamorphosed by the intrusion of the porphyry dykes. Lieut. 

 "Washington, on his first day's journey south of Tangier, refers 

 to the occurrence of rounded schistose hUls about 300 feet high, 

 strike north-west and south-east, dip 75° south-west, containing 

 mica-slate with veins of foliated quartz ; but I have no recollec- 

 tion of observing any such metamorphic rocks between Tangier 

 and Tetuan. 



(f ) Porphyrites. — Of the eruptive rocks of the Atlas, por- 

 phyrites and porphyritic tuffs occupy by far the most prominent 

 position, forming the great mass of its ridge. 



On entering the lateral valleys, after crossing the vertical 

 shaly beds, great masses of red porphyrites and tuffs are met 

 with, associated with specular iron and occasional green por- 

 phyries. The harder portions of the latter are seen as Verde 

 antique pebbles in the river-beds ; but we failed to detect this 

 in situ. From the large proportion of tuffs that occurs the 

 porphyrites appear to be interbedded, and are possibly contem- 

 poraneous with the vertical grey shales to which they are 

 adjacent. They are overlapped unconformably by the Red 

 Sandstone and Limestone series of Cretaceous age. The late 

 Mr. D. Forbes informed me that they bear a strong likeness to 

 the porphyrites of the Andes, of Oolitic age ; but beyond the 



