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Our knowledge of the geology of the country occupied by these tribes, has not, since Captain Pemberton wrote his Report on the Eastern Frontier, been in the least improved. The universal prevalence of dense and impervious forests, extending from the summits of the mountains to their bases, he observes, has restricted observations to those portions that have been laid bare by the action of the torrents, and to some few of the most conspicuous peaks and ridges. In that portion of the tract which extends between Munnipore and Cachar, a light and friable sandstone of brown colour and a red ferruginous clay, are found to prevail on the lower heights. On reaching the more lofty elevations, these are succeeded by slate of so soft and friable a nature, as in many instances to be little more than an indurated clay; it is distinctly stratified in very thin layers which generally dip slightly to the southward. Petrifactions of the different species of woods growing on the borders of the nullahs are very numerous. Among the central ranges, he states, West of Munnipore, lime-stone has been found cropping out from the banks of the streams, and it has since then been found in the North, South, and East. The rocks found on the hills between the Munnipore and Kubbo valleys are, on the Munnipore side, composed of different varieties of sand-stone and slate, (73) more or less compact in its structure. On the Kubbo side horn-blende and iron-stone are found with agalmatolite and fullers earth which are dug from the ground not far from Morch. North of Munnipore the rocks become more solid and compact; and the great central ridge about where the Gnamei tribe dwells is composed of hard grey granular slate at the ridge, having about the base boulders of granite. |
