96 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jail. 10, 



(3) Mica-schists of Djeb Tezah, in the Atlas, south-west of Mo- 

 rocco, pierced with eruptive porphyritic dykes, which may be an 

 altered condition of the vertical grey shales adjacent to the inter- 

 bedded porphyrites. 



These rocks are our starting-point, respecting which there is no 

 evidence of their age, or even relative age. 



(4) We now come to a long period of denudation of the Atlas 

 ridge, and its sculpturing into hill -and- valley contour, before the 

 deposition of the Red-Sandstone and Limestone series. 



(5) The deposition, over what is now the Morocco plain, of the 

 Cretaceous E,ed-Sandstone and Limestone series (and beds possibly 

 of Miocene age), which also occupies preexisting valleys in the older 

 porphyrites of the Atlas. 



(6) The intrusion of diorite into the porphyrites and porphyritic 

 tuffs, probably accompanied by a further elevation of the Atlas range, 

 disturbing the stratified Red-Sandstone and Limestone series, throw- 

 ing them into a synclinal trough, from which the beds rise north- 

 wards towards the plain, and southwards towards the Atlas. 



(7) A further long period of denudation of the Red- Sandstone 

 and Limestone series, rescooping out the lateral valleys of the Atlas, 

 in continuation of the valleys that existed in the porphyrite ridge 

 prior to their deposition, and also denuding the beds in the Morocco 

 plain to the extent of at least 300 feet, leaving isolated remnants 

 as flat tabular hills rising above the present general level of the plain. 



(8) A further emission of red porphyrites through the stratified 

 beds of the plain, which may have been contemporaneous with the 

 eruption of the red-porphyry dykes of Djeb Tezah, in the High Atlas. 



(9) A post-Cretaceous eruption through the Red-Sandstone and 

 Limestone series of a multitude of dykes of amygdaloid basalt, the 

 age of which is uncertain. 



The more recent changes commence with : — 



(10) The formation of gigantic boulder-beds flanking the northern 

 escarpment of the Atlas plateau, and spreading down in great mounds 

 and undulating ridges from a height of 3900 feet to the borders of 

 the plain, 1900 feet above the sea, with a range in vertical height 

 of about 2000 feet, and extending up the entrances of several of the 

 lateral valleys, as well-defined and symmetrical moraines. 



(11) The formation of moraines at the heads of the Atlas valleys, 

 commencing at a height of 5800 feet, and spreading up to the cliffs 

 of the Atlas ridge, to a height of between 7000 and 8000 feet, with 

 a terminal angle of repose 850 feet in vertical height. 



(12) The formation of a plain of shingle behind the moraines, at a 

 height of about 6700 feet, which seems to be the bed of a small lake. 



(13) The recession and extinction of glaciers in the Atlas range, 

 on which there is now not even perpetual snow. 



(14) An elevation of the coast-line of at least 70 feet, represented 

 by the height of the raised beaches of concrete sand at Mogador and 

 other parts of the coast, which may possibly be contemporaneous with 

 the elevation of similar raised beaches on the coasts of Spain and 

 Portugal, and with the raised beaches of our south-western coast. 



