376 Till-: i-AL'Ll S\.STKMS IN SOUTH OF SOLTH AFRICA. 



btr,iLi', and Zwartljerg ranges, is the dominant, and tlie norlh and 

 soutii line is the snl)nr(hnate fold-system, this latter line inclnding 

 the Great Winter Hoek, the Witzenljerg, the Cold Bokke\cld 

 monntains. and the Cedarbergen. A glance at the nia]) w dl 

 show that the east and west mountains cover a far hroader 

 belt, and are InUtressed In' a number of i)arallel subsidiary ranges, 

 such as Touws Uerg, \\ arm Water Berg, and S(» on. For this 

 reason the folds streaming from the junction of the two main 

 lines trend in a S.S.W. line instead of a S.W. one, the northern 

 end of them 1)eing, as it were, puslied over to the west. There 

 are somct fractures accom|Kuing these folds in parallel position, 

 but the more important ones are at right angles to this direction. 

 We have already dealt with the Ceres monoclines, which have 

 this direction, namely, P2.S.E. (which is at right angles to 

 S..S.\\'. ). but the greatest of all the South African faults belongs 

 to this set and lies in this direction, and is the great Worccstcr- 

 Swellendam fault. The Worccstcr-Swellendam fault, then, 

 mav be defined as a cross fault in the area of schoantiif/ or 

 junction of the two main mountain ranges of Cajje Colony. It 

 is as if the two ranges, the X.S. and E.W. mountains, in joining 

 issue at the angle, raised the portion of the earth's crust above 

 the bearing cajjacit}' of the span, and consequently the outside 

 corner was broken ol^ and sank. The inside of the l)end was 

 also rucked u\) above its natural level and also collapsed. ])ro- 

 ducing the monoclines of the north and east of the Warm 

 Bokkeveld. 



The Worcester-Swellendam fault has a maximum throw 

 of two to two and a half miles in the central portion between 

 Worcester and Robertson. Here the Ecca lies against the 

 Malmesbur}' beds, with no surface indications at all that th-M-e 

 has l)een this great disturbance; one can stand with one foot on 

 the Afalmesbury and the other on the luxa, with the fault be- 

 tween. Tt was only when 1 found impressions of the leaves 

 of the Karroo fern Cai;(/aiin)ptcris in i!ie shales which., u]) to 

 then, had been regarded as Malmesbury beds, that the nature 

 of this great structural feature became evident. Great as the 

 throw of this fault is. it is by no means exceptional ; (jn the 

 east coast of India and under the Himalayas in Assam similar 

 faults occur, letting down tongues of what are actually Karroo 

 beds, though the}- are called in India (^londwana beds, into and 

 against the gneiss and granite which takes the j^lace of the 

 Malmesbury beds. The Gondwana series in India is somewhat 

 different from, although it is contemporaneous with, our Karroo 

 beds, and contains the same fossils. The main difference is 

 that these Indian equivalents contain vast quantities of coal, 

 so that, as the extent of the coalfields depends on the faults, 

 the latter have been very thoroughly studied. The Indian faults 

 reach a maximiun of 20,000 feet downthrow, or almost double 

 that of tlie Worcester-Swellend'uu fault. 



