The inferior mountains are distinguished from the central, by being divided into beds.

We have next to investigate the character of those intermediate masses which constitute the greater part of all hill scenery, forming the outworks of the high ranges, and being almost the sole constituents of such lower groups as those of Cumberland, Scotland, or South Italy.

All mountains whatsoever, not composed of the granite or gneiss rocks described in the preceding chapter, nor volcanic (these latter being comparatively rare), are composed of beds, not of homogeneous, heaped materials, but of accumulated layers, whether of rock or soil. It may be slate, sandstone, limestone, gravel, or clay; but whatever the substance, it is laid in layers, not in a mass. These layers are scarcely ever horizontal, and may slope to any degree, often occurring vertical, the boldness of the hill outline commonly depending in a great degree on their inclination. In consequence of this division into beds, every mountain will have two great sets of lines more or less prevailing in its contours: one indicative of the surfaces of the beds, where they come out from under each other; and the other indicative of the extremities or edges of the beds, where their continuity has been interrupted.