The geology of Abyssinia also favours these strange alterations of its own face; for it is composed almost entirely of volcanic rocks, easily decomposable, the operation, in fact, scarcely requires the aid of water to occasion it; for the atmosphere alone crumbles the hardest rocks, in the course of one year, into a stratum of loose earth; and water appears to be merely the carrying agent, to remove the soft soil, and expose a fresh surface to the action of the air. It is this which adds so considerably to the fertility of the Argobbah counties, situated on the scarp of the Abyssinian table-land; for every fresh year, virgin earth of the most fertile capability, is offered spontaneously, for the benefit of the cultivator, to whom, in this situation, the use of manure is unknown. Rain, however, aids considerably in removing vast portions of the table-land; for during the wet season, generally some few days after the commencement of the rains, and again, near its close, severe thunder storms, with slight earthquakes, occur; and the devastation which results, is not so much to be attributed to the latter, as it is to the previously fallen rain; which, having penetrated to a certain depth of the easily disintegrated rock, the least agitation brings down immense quantities, from the nearly perpendicular cliffs. An earthquake scarcely perceptible, and which, perhaps, is only consequent upon meteoric explosion, by the reverberating vibrations being communicated to the loose, yet prominent surfaces of the hilly scarp; there always precipitates ruinous masses of earth and rock, whilst not a trace of its effects can be perceived upon the table-land. This is the real character of all earthquakes in Abyssinia I have witnessed; and although the death of twelve or fifteen people, have been consequent, it has only been in different situations of peril, the proper precaution could have easily obviated, as it was where denudation had been long undermining the foundation of their houses, or of those on the terraces above; and which, when a moment of extraordinary atmospheric commotion occurred, were shaken from the sides of the valleys into the stream below. No leaping of the earth, or those violent commotions, which mark these convulsions in other countries, occur in Shoa. In Ankobar, during the severest landslips, for they are nothing else, a loose stone building thirty or forty feet high, and a still more rickety arch built by Demetrius, although in exposed situations, were not affected in the least.