TliK FAULT SYSTK.Mi; IN SOUTH OF SOUTH AFRICA. 3(19 



result a tension ensues, causing the faults. There may Jje 

 cautious mountain ranges where the folding is just equal to what 

 the pressure demanded, but I do not know of them. Nature, 

 even in her grander works, shows a generous recklessness, and 

 this makes our mountains more interesting than had they Ijeen 

 huilt in a sjjirit of hard calculation. Faults, on the other hand, 

 may occur without any [Pressure preceding or following them. 

 The whole of .Vfrica, leaving out the Atlas Mountains on the 

 north-west, together with the peninsula of India, and in all pro- 

 bability the Indian Ocean between them, is a faulted block of 

 the earth's crust. It is true it is bounded on the north by the 

 great folds of the Alps-Himalaya System, which are contem- 

 poraneous with the post-Cretaceous faults, and so in a way we 

 may say that the faults of Africa have some relationship with 

 folds. In this matter, however, tlie area is so vast that no one 

 has yet been able to grasp the general outlines of the case. To 

 me it has seemed as if the faulting, fracturing, or smashing up 

 of the Indo-African Continent resulted in a spurting up of the 

 earth's crust in a ridge round the edge, this ridge being now 

 represented by the Ali)s, Himalayas, and Burmese Mountains, 

 with the Aleutian chain, the Rocky Mountains, and the Andes 

 as an outer and lesser rim. Such a smashing up could only 

 have been etlected by a blow from the outside, whicli could lie 

 brought aboiu b\- the in falling of a giant meteorite on to the 

 earth. A meteorite 1,000 miles in diameter, or, say, half the 

 diameter of the moon, could have fallen into the Indian ( )cean 

 between the Peninsula of' India and Somaliland, north of the 

 Sevchelles, and had it so fallen in the period between the 

 Cretaceous and Eocene periods, it would have produced all the 

 fracturing observed. 



As regards the ridging u]) of the earth round the fractured 

 ]jortion. T liave endeavoured to reproduce the conditions experi- 

 mentallv 1)\- m< muting a large glo1)e of modelling clay on a 

 ])otter's wheel, spinning this round at a great rate, and then 

 shooting on to it a ball of clay of the same relative dimensions 

 to the laree gflobe as a meteorite of a 1,000 miles diameter wotild 

 have to the whole earth, that is to say, the projectile w^as one- 

 eighth of the diameter of the globe. I obtained a splintered 

 area Avith a ridge round it, where the ball of clay entered the 

 revolving globe, but the effects were not sufficiently clear for 

 demonstration purposes. The experiment failed because of 

 the want of tenacity of the modelling clay when spun round so 

 rapidly, for the large globe tore away from its axis. It is neces- 

 sary to have a more or less plastic substance, as very large 

 objects as the earth as a whole, and even a meteorite half the 

 diameter of the moon, act as plastic bodies owing to the want 

 of cohesion due to their bulk. I have not yet succeeded in find- 

 ing a suitable medium. The whole experiment was designed 

 to i^how more than the fracturing and ridging of the globe. 

 The area struck by the infalling body became dented; I had 



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