70<± GEOLOGY OF CERTAIN DISTRICTS OJF CAPE COLONY. [Nov. 1911. 



and usually ranging from 1000 to 2000 feet in altitude, reaching 

 3000 feet only in the neighbourhood of Robertson, where a 

 large intrusion of granite forms a conspicuous peak of 3100 feet. 

 Below and in front of these foot-hills stretches the broad valley of 

 the Breede River, which is in parts diversified by hills of con- 

 siderable height, but sometimes forms a plain as much as 1 miles 

 wide : this is bounded on the south and west by the Zouder Einde 

 Mountains and other ranges. In the north-western part of the 

 district, north of the Hex Biver, the trend of the principal 

 northern chain undergoes a change, curving round to the north 

 and becoming parallel to the other mountain-chains of the coastal 

 region of Western Cape Colony ; whereas the Langebergen beyond 

 Swellendam assume an east-and-west trend, parallel to the other 

 ranges of the south coast. As will be shown later, this change of 

 direction is intimately connected with geological structure, and is 

 of the utmost importance in the study of the tectonics of the 

 district. 



The scenery is characteristic and in parts very beautiful, especially 

 in the mountain -ranges, where some of the passes, such as the Hex- 

 River Poort and Kogmans Kloof, show scenes of great magnificence. 

 The contrast is very striking between the rugged and exceedingly 

 steep mountains of Table Mountain Sandstone and the wide alluvial 

 plain of the Breede River at Worcester, which has been carved out 

 of the softer beds of the Bokkeveld, Karroo, and Enon formations. 

 The scenery of the district can be well seen from the railway, since 

 the main line from Cape Town to Kimberiey and Johannesburg 

 runs through the Hex-River Pass after leaving Worcester, and 

 the line of the New Cape Central Railway runs along the foot of 

 the Langebergen from Worcester through Robertson and Ash ton, 

 towards Swellendam and the south coast. The region is, therefore, 

 easily accessible. 



IV. The Worcester District. 



The town of Worcester lies on the northern edge of the great 

 alluvial flat of the Breede Valley, some 5 miles south-west of 

 the mouth of the Hex -River Pass, which is now the principal 

 line of railway-communication between Cape Town and the Orange 

 Free State and the Transvaal. It forms, therefore, a convenient 

 centre and starting-point for the investigation of the district. The 

 outcrop of the Malmesbury Series is here unusually wide, extending 

 over a total distance of some 6 miles ; consequently this is a 

 specially favourable locality for studying the general character 

 of the Series. The Malmesbury rocks here vary considerably in 

 lithological character, but the general conformation ot the ground is 

 very uniform throughout. They form an expanse of comparatively 

 low, rounded, rolling hills, varying in height from about 1000 to 

 1500 feet, diversified occasionally by small crags — or kranzes, in 

 the local idiom. Along the river-courses there is usually a good 

 deal of recent alluvium, and in some parts exposures are rather 

 deficient. The junction between the Malmesbury Series and the 



