The chief physical feature of Madagascar is the central mountain mass, which commences with lofty mountains at the north end of the island, and retains them till within a moderate distance of its southern cape. The entire central line is high ground and only its two sides are level plains along the east and west sea-coasts. The central mass is by no means uniform in its appearance. We have already shown how, on ascending to the interior from the east coast, the traveller meets and successively mounts three lofty mountain walls, each supporting a broad terrace behind it. The first of these, west of Ampásimbé, rises 900 feet: beyond Befórona, the second terrace is 1400 feet higher: the third ascent at Angávo carried us up 1620 feet on to the highest part of the Imerina plain. The central plateau has a general height of 4000 feet: at its widest part it is ninety miles in width; in the narrowest it is about thirty miles. This plateau is somewhat over two hundred geographical miles in length. It abounds in ridges and detached hills of gneiss and granite, which give wonderful variety to the scenery; and at several points these rocks spread out in wide, lofty and barren moors. The rugged ridges enclose broad basins of the sedimentary clay, and the numerous streams of pure water furnish abundant sustenance for the rice crops, which form the principal food of the people. As this central level is reached by great terraces from the east, so on the north, south and west, the traveller descends from it on to other terraces, going gradually lower and lower, until he reaches the level of the sea. It was a matter of deep interest to Mr. Pillans and myself that we descended on to the first terrace at several points; at Ambohimandroso, beyond Lake Itasy, and in the valley of Ankay, before we finally followed down the entire series of steps on our way to Mojangá. The fact that to so large an extent the island consists of red clay, and appears to have been at some time perfectly buried in it, accounts for the peculiar form of its terraces and of the basins which they sustain. The enormous volcanic forces hereafter to be described may have been required to break the granite rocks and render them available for the use of men: but water has exerted a mighty agency likewise on the island: and whether by rains or streams or waterspouts, in the bursting of lakes or by gentle showers, during long, long ages it has been ploughing and moulding and shaping the land, and it is moulding and shaping and beautifying it still.