Directly south of its extremity are the islands of Makawar and Mayitib, which, like Rawaya, enclose a deep basin of water (40 fathoms) on their west side, while on the east depths of 200 fathoms are found only a mile and a half from Mayitib, and 300 fathoms only three miles away, while half a mile from the islet of Shambaya the same depth occurs. In comparison the elevation of the peninsula, and even of the islands, is very trifling, and the difference of level between them and the maze of reefs which separates them absolutely negligible. Indeed [Illustration: Diagram 9. Section through Rawaya and Makawar.] Rawaya is extremely low, its average being about ten feet above the sea, the areas of its two hills, Jebel Têtawib in the north, and Jebel Abu Shagara in the south, being inconsiderable, and their heights only about 40 and 127 feet. Further, an inspection of the ground shews that these hills are merely parts of the peninsula which have been thrust up to a higher level (see Diagram 9), and even on Makawar, where much of the island attains a height of over 250 feet with summits of 300 feet, the two ends and west side are low like Rawaya. In short, Rawaya, Makawar and the reefs between and about them are obviously one continuous ridge, the middle part of which is slightly lower, and, by coral growth and wave erosion, has been built up and cut down into the level area of reefs we now find there. [Illustration: Fig. 85. Peninsula of Rawaya and reef systems connected with it The narrow fringing reef along shore of mainland shaded as are coral beds in Khor Dongonab. Small Islands are black. Dotted areas are reefs free from coral. -·-·-·-·- 10 (and in south basin 20) fathom line. --------- 100 fathom line.] The conversion of such low-lying land as Rawaya into a reef maze follows at once from the action of the sea, restrained by coral growth, described in Chapter VIII, but the diagrams make the case clearer. A is the first stage, the thin line representing the outline of a partly submarine hill range, the undulations of which are much exaggerated in the diagram. The horizontal dotted line is the sea-level, so the diagram represents one summit above the sea, an island, another submerged, and a third emerging to the right. [Illustration: Diagram 10. Conversion of a line of low hills, partly submarine, into a maze of surface reefs A First stage. B after elevation and second period of abrasion. ----- sea level. [Legend: wavy lines] additions made by coral growth. Coarse shading = remains of original hill after abrasion. Fine shading = coral mud or sand.] In A the first summit to the left appears above water as a rounded island, which is cut down considerably and much of its area converted into reef flat, and the deep lagoon to the right is narrowed by coral growth on both this reef flat and over the next summit, as indicated by zigzag shading in the diagram.