which are ready to split up and crumble away along the planes of bedding, or of jointage, whether visible or concealed, by which they are traversed. Then when a thunderstorm happens to come, with its deluge of rain, raising in a few moments a torrent which rushes down every dell, and converts waterless valleys into impetuous river-beds, the stones give way in all directions, and are swept down and spread over the plains to a distance scarcely credible. In such a way may we explain the striking results of atmospheric denudation in this region,—the formation of the lofty precipices, the grand escarpments, the jagged peaks, the long and deep valleys, and the presence of the alluvial detritus which overspreads the spacious plains.
Fig. 14.—Terraces above the descent to The Ghôr.
Beds of white marl and silt, formerly the bed of the ancient Salt Sea (Bahr Lut).
About 1,050 feet above its present level.
We were now on the road traversed by Robinson, Palmer, and Drake. It was difficult to traverse, being formed alternately of the beds of torrents and of soft sand dunes piled up by winds from the south-west, and often rising high on the sides of the limestone cliffs on our right; for here the limestone forms the flanks of the Wâdy el Arabah on both sides. On our left the great marly plain, the ancient floor of the Salt Sea, stretched away to the banks of the Jeib, and the escarpment of the Tîh beyond. We passed several parties of the Alowîns, and of other tribes about Petra, returning with their little donkeys laden with corn, which they had purchased from the Ghawarnehs of Es Safieh, and were carrying home for the use of their families.
On crossing the Wâdy T'lah, a deep ravine, descending from the mountains on the right, and giving rise to a dense vegetation of tamarisks, thorny acacias, and bamboo canes, we found ourselves for the first time
