This work being accomplished, and the day being now fully spent, the party bade the shores of the sea farewell; and, weary with the fatigues and excitement of the day, they began, with slow and toilsome steps, to reascend the path toward their encampment by the fountain. They at length arrived at their tent, and spent the evening there to a late hour, in writing out their records of the observations which they had made, and of the adventures which they had met with during the day. From time to time, as the hours passed on, they looked out from their tent to survey the broad expanse of water now far below them. The day had been sultry and hot, but the evening was cool. The air was calm and still, and the moon rising behind the eastern mountains shone in upon their encampment, and cheered the solitude of the night, illuminating, at the same time, with her beams, the quiet and lonely surface of the sea.
At a subsequent period of his tour in the Holy Land, Robinson approached the Dead Sea again, near the southern extremity of it, and there examined and described a certain very remarkable geological formation, which is justly considered one of the greatest wonders of this most wonderful valley. It is called the Salt Mountain of Usdum. It is a lofty ridge that extends for a great distance along the shore of the sea, and consists of a solid mass of rock-salt. The situation of this mountain, as will be seen from the map, is on the southwestern shore of the sea. There is a narrow tract of low and level land between the mountain and the water. The road passes along this plain, close under the cliffs, giving the traveler a very convenient opportunity of examining the formation of the mountain as he journeys with his caravan slowly along.
The existence of such a mountain of salt was asserted by certain travelers many centuries ago, but the accounts which they gave of it were not generally believed, the spot being visited too seldom, and the accounts which were brought from it being too vague and imperfect to confirm sufficiently so extraordinary a story. Robinson, however, and other travelers who have, since his day, fully explored the locality, have found that the ancient tales were true. The ridge is very uneven and rugged, its summit and its sides having been furrowed by the rains which sometimes, though at very distant intervals, fall in this arid region. The height of the ridge is from one hundred to one hundred and fifty feet. The surface of the hill is generally covered, like that of other rocky ridges, with earth and marl, and sometimes with calcareous strata of various kinds, so that its true character is in some measure concealed from ordinary and casual observers. The mass of salt, however, which underlies these superficial coverings, breaks out in various places along the line of the hills, and sometimes forms perpendicular precipices of pure crystalized fossil salt, forty or fifty feet high, and several hundred feet long. The traveler who beholds these crystaline cliffs is always greatly astonished at the spectacle, and can scarcely believe that the mountain is really what it seems, until he has gone repeatedly to the precipice and broken off a fragment from the face of it, to satisfy himself of the true character of the rock, by tasting the specimen.