ROCK-FOLDS 



581 



S-fold, faulted between the syncline and anticline ; the sandstone 

 for the most part is thin-bedded, and would, from the multitude 

 of bedding planes, contain a considerable amount of moisture. 

 Interbedded with this is a massive bank of quartzite, about 

 4 ft. thick, and the rate of flow of this and of the thin-bedded 

 sandstones caught in the nip of the bend was very different, as 

 is apparent in the sketch. The actual tensile strength of a small 

 bar cut from either the thick bed or from one of the thin beds 

 would be about the same, and certainly the difference would not 

 be sufficient to account for the flow in the axis of the anticline ; 



E.H.L.S. 



Fig. 7. 



generally, therefore, taking the evidence from this small fold, 

 together with that of the Tygerberg, this type affords abundant 

 evidence in favour of the solution and redeposition theory. 



(c) Folds which have, as it were, tumbled on themselves, and have 

 thereby produced vertical pressure. — I take my illustration of this 

 type from the great gap sawn through the Zwartberg Mountains 

 near the eastern end, called Meiring's Poort, though similar 

 examples may be seen in any of the western poorts. The 

 mountains rise to nearly 7,000 ft. above sea-level, while the 

 river which has sawn through them lies only between 1,000 

 and 2,000 ft. above. Towards the southern end the anticline 



