Abstract
The Karachi region presents the landforms of varied nature and origin ranging from the arid to fluvial and marine landscapes. This assemblage of landscape reflects polygenesis in origin. Structurally the whole region of Karachi presents a series of plunging folds trending NE-SW which is name after the localities as Cape Monze, Pir Mangho, Drigh road and Landhi-Korangi anticlines. These four anticlines are alternated with three synclines named as Laljee, Lyari and Malir synclines which are traversed by these sizeable seasonal streams. The landscape features show a marked structural and lithological control although much of land surface is irregularly blanketed by aeolian sandy/silty cover and spotted with gravely mounds of variable dimensions depicting the remnants of former fluvial terraces. The whole area of Karachi region can be divided into six morphological zones from the hinterland to the coastal margin based on the nature and origin of the surface, relief conditions and the landform assemblages. Apart from the other processes of sub-aerial erosion, the process of differential erosion played a dominant role in shaping the landform on the alternately placed folded beds of hard and soft nature. Ridge and valley type topography is well developed whereby the transcurrent faulting has off-setted and truncated the ridges. Through the fault gaps, the opposite pediments are communicating and joined. The coast line is mostly cliffed and conspicuous signs of emergence in near geological past are present. Regression and degradation phenomenon is commonly along the coast line, although some parts show clear signs of progradation. Cumulatively the shoreline is of mixed type. The drainage networks mostly show adjustment with the regional and local grains of area. Presently, the region is passing through an immense phase of degradation in general. A brief note on the vegetation of various habitat types of Karachi is included. Euphorbia caducifolia, Acacia nilotica, A. senegal, Capparis decidua, Commiphora wightii, Salvadora persica, S. oleioides, Prosopis juliflora, P. glandulosa, Tamarix indica, Arthrocnemum indicum, Urochondra setulosa, Ipomoea pes-caprae, Halopyrum mucronatum, and Avicennia marina are the important characteristic species of various habitats. P. juliflora, a species of high ecological amplitude is the most dominant species throughout the area
