330 THE UMZAMBA BEDS 



another similar bed at a slightly higher or lower level 

 takes its place. 



The sandy calcareous clays are blue in colour on fresh 

 unweathered surfaces, and they are so tough that the 

 fossils contained in them are only with difficulty ex- 

 tracted from the rock, but the outer inch or two of the 

 exposed outcrops are altered to a soft brown clay, from 

 which the fossils are easily obtained by scraping away 

 the decomposed rock with a knife. 



The following section measured on the low cliff near 

 the Umzamba mouth illustrates the nature of the suc- 

 cession in these rocks : 



Ft. In. 



13 Shelly limestone 10 



12 Tough sandy clay weathering brown . . 1 4 

 11 Shelly limestone . . . ..06 



10 Tough sandy clay 10 



9 Shelly limestone 04 



8 Tough sandy clay . . . . .36 



7 Shelly limestone 10 



6 Tough sandy clay ..... 3 

 5 Black impure limestone with many shells 6 



4 Black shale 10 



3 Oyster-bed .02 



2 Fine gravelly conglomerate . . .03 

 1 (At base) Conglomerate with pebbles im- 

 bedded in broken shells ; many -fossils ? 



13 _3 



The coarse bed at the base of the section is exposed 

 on the shore at low water on both sides of the mouth of 

 the Umzamba, but the extent of the rock laid bare at 

 low tide varies, much of it being at times buried under 

 the sand thrown upon the beach by the waves. A 



