▁so ▁during ▁the ▁past ▁ 2 0   mill ion ▁years . ▁The ▁present ▁coast line ▁was ▁therefore ▁once ▁part ▁of ▁the ▁under water ▁contin ental ▁sh elf , ▁which ▁contains ▁very ▁few ▁deep ▁rav ines ▁or ▁g org es . ▁In ▁contrast , ▁a ▁subs iding ▁coast line , ▁like ▁Norway ' s , ▁tends ▁to ▁become ▁deeply ▁ind ented ▁where ▁the ▁sea ▁has ▁flo oded ▁old ▁river ▁g org es ▁and ▁gla cial ▁valle ys . ▁ ▁Regional ▁divisions ▁ ▁High vel d ▁ ▁The ▁Central ▁Pl ate au ▁is ▁divided ▁into ▁several ▁distinct ly ▁different ▁regions ▁( though ▁with ▁very ▁vague ▁boundaries ), ▁largely ▁as ▁a ▁result ▁of ▁the ▁ra inf all ▁distribution ▁across ▁South ▁Africa : ▁wet ▁in ▁the ▁east ▁and ▁increasing ly ▁d rier ▁and ▁more ▁ar id ▁in ▁the ▁west . ▁The ▁wet test ▁and ▁most ▁fert ile ▁portion ▁of ▁the ▁Central ▁Pl ate au ▁is ▁the ▁High vel d , ▁which ▁occup ies ▁the ▁central ▁eastern ▁portion ▁of ▁the ▁Pl ate au . ▁It ▁is ▁generally ▁between ▁ 1 , 5 0 0 ▁– ▁ 2 , 1 0 0   m ▁above ▁sea ▁level , ▁highest ▁on ▁the ▁edge ▁of ▁the ▁Esc arp ment ▁to ▁the ▁east ▁( the ▁M p um al anga ▁D rak ens berg ), ▁and ▁s lop ing ▁down wards ▁to ▁the ▁south ▁and ▁west . ▁Its ▁southern ▁boundary ▁is ▁often ▁taken ▁to ▁be ▁the ▁Orange ▁River , ▁from ▁where ▁the ▁continu ation ▁of ▁the ▁plate au ▁is ▁known ▁as