TERTIARY AND RECENT DEPOSITS 391 



of clay, sand and subangular fragments of vein-quartz 

 and other rocks that do not decompose under the in- 

 fluence of the weather, cemented together by the iron 

 oxide. 



Along the edges of the Cape Flats near the high 

 ground of the Peninsula and the Tyger Berg the 

 laterite, or ironstone as it is usually called, is found 

 a few feet below the surface. Farther inland, in the 

 Malmesbury, Paarl, Caledon and other divisions near 

 the coast, where there is no general covering of sand 

 as on the Cape Flats, the laterite lies just below the 

 soil, or is exposed at the surface, over considerable 

 areas of flat and slightly inclined ground. It is rarely 

 or never found in its typical form on steep slopes, al- 

 though even in such situations the subsoil is in places 

 partly cemented into a fairly hard substance by ferru- 

 ginous matter, thus making an approach to the laterite 

 of the lower ground. 



The formation of the laterite is due to the concentra- 

 tion of the iron oxide near the surface in the decomposed 

 rock or subsoil, occasionally in sandy soil that has been 

 brought to its present position by water. The nature 

 of the clay that accompanies the laterite in many places, 

 especially where it lies upon clay slates, has not yet 

 been ascertained. 



The high-lying lateritic rocks are closely connected 

 with the older gravels and alluvial deposits, and are 

 now represented by mere remnants, but the low-lying 

 ones are in process of formation to-day. 



Very similar looking laterites appear to have been 

 derived from rocks of diverse natures, such as granite 



