382 



SURFACE QUARTZITES 



In the Malmesbury, Piquetberg, Clanwilliam and Van 

 Rhyn's Dorp Divisions surface quartzites are met with 

 in many places on the coast side of the Olif ant's River 

 Mountains and the other ranges in connection with 

 them. The quartzites are usually underlain by sandy 

 clay or gravel into which they grade. By an increase 

 in the amount of ferruginous colouring matter they 

 become very similar to the laterites, and on the Van 

 Rhyn's Dorp coast the latter pass into coarse con 

 glomerates containing the shells of living species of 



"*= ' \ i . ~ __. ___^ ii-rjnf/m^M^- 



FIG. 29. Section in cutting on railway close to Moorreesburg Station : 

 1. Sandy soil; 2. Clayey sub-soil full of ferruginous nodules and con- 

 cretions ; 3. Decomposed Malraesbury slates ; 4. Quartzite masses. 

 Length of section, 24 feet. 



marine forms, raised beaches which lie from 50 to 100 

 feet above the high-water mark. 



An interesting occurrence of these quartzites was ex- 

 posed in a ballast pit on the down side of Moorreesburg 

 station in 1905 ; it is illustrated by Fig. 29, which is 

 drawn to scale. The quartzite forms flat masses, with 

 irregularly curved surfaces, lying horizontally in a sandy 

 and clayey ferruginous layer (laterite) under the soil or 

 projecting into the latter. It is a bluish white rock 

 made of angular chips of quartz and sand just like those 

 in the laterite, cemented together by quartz ; the outer 



