After a night's refreshing bivouac on the sand, under the palm trees of Wadi Tor, we rose at sunrise on the 10th of June, 1840, mounted, and travelled slowly among some low sand hills in a northerly direction, almost parallel with the eastern shore of the Red Sea. As we emerged from the mouth of a small defile, the waters of this sacred gulf burst on our view; the surface marked with annular, crescent-shaped, and irregular blotches of a purplish red, extending as far as the eye could reach. They were curiously contrasted with the beautiful aqua-marine of the water lying over the white coral reefs. This red colour I ascertained to be caused by the subjacent red sandstone, and reddish coral reefs; a similar phenomenon is observed in the straits of Babel-mandeb, and also near Suez; particularly when the rays of the sun fall on the water at a small angle. The low hills of the defile were covered with fragments of brown, red, white, and black chert, many of them coated with a white mealy enduit, flattish and singularly honeycombed. Hillocks of a considerable size were often wholly composed of similar fragments. In a pass to the left, at the foot of some cliffs about fifty feet high, imbedded in a stratum of friable earthy sandstone, we observed a layer of fossil shells. The rock in many places is impregnated with oxide of iron, and contains thin veins of quartz resembling calcedony. From this place, our route lay along the shore of the Red Sea. High sandstone cliffs skirted the right of the path, in regular strata, dipping at an angle of 5°. E. 20 N.; direction S.S.E.