Vol. 55.] SOTTTHEEN MOROCCO AND THE ATLAS MOUNTAINS. 203' 



strips. Indeed, but for a geological phenomenon, that barrier would 

 not now exist, and the valley of Teluet would be drained into the 

 Gadat instead of into the Draa. The preservation of this barrier 

 is due to the abrupt bending over of the massive quartzite which 

 caps the friable shales of the central mass of the Atlas. From 

 being a horizontal cap resting on shales, and therefore easily under- 

 mined, it now stands as a vertical wall running across the pass, 

 and subject only to the slow erosive processes of ordinary weathering. 

 As it is, these processes have succeeded in cutting it down from it& 

 original level of over 11,000 feet to that of 8400, the height of 

 the notch which forms the Pass of Teluet. 



On crossing this pass, a great sheet of basalt is seen to have 

 been intruded between the sandstone-beds, as if to stiffen and 

 strengthen the rocky barrier of the pass. The southern slope of 

 the mountain is found to coincide approximately with the dip 

 of the rocks. 



The rapid descent from the pass brings one to the interesting 

 little valley of Teluet, the seat of the great mountain Kaidship or 

 province of Glauwa. The rocks in which it has been excavated 

 are red shales and marls, similar to those exposed around Zarktan 

 and Enzel. They are seen to be much folded, and rise southward, 

 to form the plateau of the An ti- Atlas. An examination of the 

 valley seems to point to glaciers as the chief excavating agent. Its 

 floor is now strewn with moraine-heaps and large blocks of rock, 

 many of them weighing several tons. 



Such are the chief geological characteristics of the Atlas along 

 the Gadat to Teluet. We have seen that the limestones are here- 

 some what poorly developed on the outermost flanks of the mountains, 

 and marked, as at Demnat, by the intrusion of a great basalt-dyke. 

 Proceeding southward, these limestones are observed to give place 

 to a great series of red and purple shales at Enzel, and then to a 

 sandstone series. Again, the red shales at Zarktan are followed by 

 an enormous development of grey and black shales, rising to an 

 altitude of 12,000 feet. The latter, as mentioned above, are capped 

 by a massive quartzite which, bending over, has resisted the denu- 

 dation of the southern slope and the inclusion of Teluet in the 

 drainage-system of the Gadat. In Teluet and the plateau to the 

 south, the red and purple shales once more reappear. How far the 

 three outcrops of red shales may be simply repetitions of the same 

 series by folding, or are different deposits, cannot yet be determined 

 with confidence ; and similarly, one can. only form suppositions as 

 to the relations of the grey and black shales to the red and purple 

 shales. At all events, they may be included provisionally in the 

 Lower Cretaceous Series. Thus much, however, we know, that 

 metamorphic rocks do not exist in this section, and, with the 

 exception of the basalts already named, no igneous rocks either. 

 Here also I first discovered evidence of undoubted glacial action, in 

 the debris at the head of the Gadat glen, and the moraine-heaps and 

 huge boulders of the valley of Teluet. 



