Almost all the mountains or volcanos, in the large series before noticed, are found on examination to have the same general constitution: they are striped vertically by sharp ridges, which, as they approach the foot of the mountain, take a more winding course. These ridges alternate with valleys, whose sides are of a very various declivity. Large rocks of basaltes occasionally project, and in several instances the valleys form the beds of rivers towards the tops of the volcanos; in the rainy season they all convey large volumes of water. Next in importance to this extensive series of primary mountains, there are various ridges of smaller mountains, or hills, extending in different directions, with nearly an equal degree of elevation; sometimes originating from or connected with the primary volcanos, sometimes forming independent ranges, and arising separately and at a distance from the great series. These, which have been termed secondary mountains, though evidently of a volcanic nature, differ in many particulars of their constitution from those of the larger series. They generally extend in long narrow ridges, with but a moderate elevation, and their sides are less regularly composed of the vertical ridges above mentioned. In most cases, a stratified structure and submarine origin may be discovered. They are generally covered with large rocks of basaltes; and in some instances they consist of wacken and hornblende, which is found along their base in immense piles. Hills of calcareous constitution, with only a moderate degree of elevation, occur in smaller ridges, often with a flat or tabular top; or in steep rocks and eminences. These are sometimes found in the centre of the island, covering the volcanic districts, but much more frequently near the northern and southern shores. Hills of a mixed nature, partly calcareous and partly volcanic, are also found. The southern coast of the island consists almost entirely of them, rising in many places to the perpendicular height of eighty or one hundred feet, and sometimes much higher. These, as they branch inward and approach the central or higher districts, gradually disappear, and give place to the volcanic series, or alternate with huge masses of basaltic hornblende, that appears to assume a regular stratification. At the base of these, or in the beds of the rivers which proceed from them, are frequently found various silicious stones, as common flints, prase, hornstone, jasper, porphyry, agate, cornelian, &c.