"Vol. 55.] SOUTHERN" MOEOCCO AND THE ATLAS MOUISTTAINS. 197 



The rest of the plateau is entirely occupied by the Cretaceous 

 rocks, which may be divided into two groups : (1) the Lower, or 

 Ted shales and sandstones ; and (2) the Upper, or grey and cream- 

 coloured limestones. 



(1) The red shales and sandstones are chiefly exposed, 

 owing to the comparative absence of the Upper beds, in the pro- 

 vince of Bled Hummel, which has received its name of Hummel, or 

 Bed, from the prevalent colour of the strata and soil. 



Passing eastward from Saffi over the Tertiary shell-sands of 

 Abda, the red shales are seen to rise in an abrupt escarpment several 

 hundred feet high, having a capping of white limestone of no 

 great thickness, and continue thence to the metamorphic area of 

 Eahamna. South of the Wad Tensift the Lower Cretaceous rocks 

 are almost entirely masked by the limestone, except where dis- 

 turbances of the strata have brought them to the surface. Such 

 disturbances have taken place at Jebel Hadid, south of the Wad 

 Tensift, and at the Ida Issa Mountains, south of Mogador; but 

 •elsewhere they are little seen. 



There is one feature of these red shales which is worth noting, 

 namely, the prevalence of salt-springs. Wherever the shales are 

 found, there also brine-springs occur. In Bled Hummel the brine- 

 springs are so abundant as to give rise to the small saliferous lake 

 of Zima, whence in the summer a considerable quantity of salt is 

 obtained by evaporation from the shallows and backwaters. Close 

 to Jebel Hadid are brine-springs, which are led into shallow pans, 

 where the water is evaporated. Among the shales of the Ida Issa 

 Mountains similar springs are found. Leaving, for a moment, 

 the plateau for the Atlas, one notes the same occurrence. At 

 Demnat, not only brine- springs, but extensive salt-deposits occur. 

 In the basin of the Wad Gadat there is a salt-stream ; at Asni in 

 Eeraya brine-springs well out, which supply all that section of the 

 range with salt. Other localities might be mentioned where brine- 

 springs are associated with the red shales, but these will suffice for 

 our purpose. 



(2) The Upper Cretaceous or Limestone group of Southern 

 Morocco attains an enormous development. Setting aside the 

 Atlas, these rocks are found rising to a height of over 5000 feet 

 above sea-level ; they are largely composed of limestones with white 

 marls and shales, and at places yellowish sandstones — the whole 

 resting on the red and purple shales and sandstones. 



Considered as a whole, they seem to have been but slightly dis- 

 turbed, despite their elevation to the extent mentioned, which would 

 seem to show that they were raised by some gradual movement, 

 rather than by any violent and sudden action. As might be expected, 

 however, there is more evidence of violent disturbance of the strata 

 as one approaches the principal focus of upheaval — that is, the line 

 along which the Atlas range has been squeezed or ridged up to its 

 present position. There can, of course, be no doubt that the forces 



