THE PLANT ECOLOGY OF THE COAST BELT OF NATAL. 373 



operated on a larger scale between the Anianziintoti and the 

 Umgeni rivers, whereby a wide alluvial flat, showing relics 

 of river-terraces, has been produced, cut off from the ocean 

 by sand dunes and by the consolidated calcareous sands of 

 the Bluff; Avithin this tract lies Durban harbour. 



Coming to the more detailed geology of the coastal belt, 

 the distribution of the four principal formations is briefly as 

 follows : From just north of the Umtamvuna River granite 

 is the prevailing rock with the Table Mountain Sandstone 

 building the 1300-1600 ft. plateau of the Murchison Flats 

 a short distance inland. Port Shepstone stands on one side 

 of a down-faulted basin, in the heart of which (just north of 

 the Umzimkulu River) is preserved a small area of Ecca " Coal 

 Measures " with Ecca Shales and Dwyka Conglomerate in 

 succession appearing to north-east and south-west, while the 

 palaeozoic sandstones become in turn exposed south of 

 Izotsha, where they make a plateau several miles in breadth 

 with an escarpment facing inland. The granite and gneiss 

 continue northwards in a broad belt with a number of Table 

 Mountain Sandstone outliers along the coast, the majority 

 of which are bounded in a northerly direction by faults 

 trending north-eastwards and running obliquely out to sea. 

 The largest of these builds a fairly even plateau just south 

 of the Umtwalumi River sloping seawards and with its inner 

 edge rising to 920 ft. This is continued to Isizela by a more 

 dissected and somewhat treeless slope of Dwyka Conglomerate. 

 Just south of the Umzinto River there is a small area of this 

 sandstone, while a larger one extends thence to Scottsburg, 

 in each case forming exceptionally even park-like country ; 

 sandstone outliers cap several ridges around Umzinto. The 

 Dwyka Conglomerate extends from that town northwards in 

 a narrow belt to Durban, with granite and gneiss only a few 

 miles inland and with the Ecca Shales and sometimes even 

 the " Coal Measure " sandstones along the coast ; faulting is 

 common. From the Umlazi River northwards the Table Moun- 

 tain Sandstone generally intervenes between the granite and 

 the Karroo Beds and sometimes covers fairly wide areas as 



