The physiography of the region serves to emphasise and, in part, explain the distinction between the northern (Manawatu) and southern (Horowhenua) parts which has been evident from the earliest period of settlement. Immediately south of Paekakariki the ranges rise boldly from the sea rendering access from the Wellington region difficult. In the vicinity of Queen Elizabeth Park (Paekakariki) the coastal plain has developed sufficiently to display the characteristic morphological features which lie parallel to the coast in bands that widen to the north. Behind the strand is the sand-dune country which intermingles with the adjacent peat area and dams the small streams. At Levin, consequently, dunes of considerable height (288 ft) rise above Lakes Horowhenua, Waitawa, and Papaitonga. Between the peat areas and the foothills of the range, which display cliffing associated with the earlier coastline, are small areas of sedimentary deposits (Otaki Sandstone) and piedmont fans which are preferred as the sites for farmhouses and buildings. Further north these two elements dominate the landscape. In the vicinity of Otaki, for example, the large fan of the Otaki River provides an extensive area of level country underlain by gravels, and at Levin an expanse of Otaki Sandstone gives rise to a landscape distinctive for its square-sided valleys which are hidden in the apparently flat surface, and to soils which are noted for their greater fertility.
All of these land forms are found to the north of the Manawatu River. At Himatangi the sand-dune region obtains a width of approximately 10 miles, the dunes lying like long fingers laid in the direction of the prevailing north-west wind. At Moutoa the peat and swamp zone attains its greatest extent, while the gravels of the Manawatu underlie most of the Oroua-Kairanga districts. At the Manawatu Gorge the ranges descend to a low saddle where Tertiary sediments overlie the basement of older greywackes. Between the ranges (which continue beyond the gorge and form the Ruahines) and the Rangitikei River, a new morphological element appears in the form of three low anticlinal domes, composed of sedimentary sandstones of the Hawera Series, pitching to the south-west, their axes arranged parallel to the main ranges. They give rise to the lovely “downland” associated with the Halcombe, Feilding, and Kimbolton districts. This is sheep country par excellence, for which the Manawatu is justly famous, and which serves to distinguish it again from the Horowhenua.