Characteristics and mode of formation of block mountain. Block mountain is formed from faulting and it involves the following:
(i) Two parallel faults develop
(ii) The block enclosed by the two parallel faults remains as it is
(iii) The land on either side of the parallel faults subsides
(iv) The enclosed centre-block, now up standing becomes the horst or block mountain

(b) Characteristics and mode of formation of Zengen: Zengen is formed as a result of wind abrasion. ​​​​​Zengens are formed in areas in the desert which have a surface layer to hard rock over-lying another layer of soft rock. Before wind abrasion can produce Zengen, fissures or cracks opened by very high temperature on the desert surface must have occurred on the hard surface layer. Wind abrasion then attacks the desert surface through the fissures already existing. The fissures are widened to become furrows while the blocks between the fissures (now furrows) become ridges called "Zengens"