INTRODUCTION

The Red Sea extends from the Gulf of Suez and Gulf of Aqaba in the north, to the narrow straits of the Bab al-Mandab - the Gate of Sorrows - where the Sea joins the Indian Ocean. The Egyptian Red Sea coastline includes the Gulf of Suez, the west coast of the Gulf of Aqaba and the northernmost third or so of the west coast of the Red Sea itself. The Gulf of Suez is connected to the Mediterranean through the Suez Canal in northern Egypt, which makes it an important shipping route. Actually, the Red Sea has been a major trading route since ancient times: important commodities have included frankincense (a tree from the Horn of Africa) and coffee (first shipped to the West from the Red Sea port of Mokha in Yemen - hence Mocha).

RED SEA FORMATION AND STRUCTURE

The Red Sea is an example of a newly forming ocean: the African and Arabian continents are moving away from each other and rifting apart to form new crust under the Red Sea, which is gradually getting wider. All the world's oceans were formed by continents splitting apart in this way and were once geologically similar to the Red Sea. The process is visible in the way that the African and Arabian coastlines of the Red Sea fit together like a jigsaw puzzle, except in the very south where the rifting process has lifted a piece of ocean floor up above sea level to form the basaltic mountains of Eritrea and Ethiopia. Geologically speaking, the Red Sea is very young. It started to open about 25 million years ago, some 40 million years after the extinction of the dinosaurs.

During the process of its formation the Red Sea was at various times connected to the Mediterranean, but only became connected to the Indian Ocean about 5 million years ago - very recently in geological time.

Seawater flooded newly forming sea several times and then dried up when the movement of the continents cut the connection. This has left huge deposits of salt buried under the sea bed. Under pressure, salt domes up and pushes towards the surface, causing islands where it lifts the seafloor up. Many of the islands in the Red Sea, including some of those around Hurghada in Egypt are formed in this way. Marine life in the Sea was killed each time the Sea was cut off since it would have become a highly salty brine lake, below sea level - rather like a huge version of the Dead Sea. The fossil skeletons of decomposing marine organisms form the oil and gas deposits which are mined along the Egyptian and Arabian coasts today.

The rift in the Earth's crust under the Red Sea means that it is deep (over 2,000 metres in places) and geologically active. Its deepest areas have numerous volcanic vents, where new crust is formed from magma brought up from the Earth's mantle. Seawater percolates through these vents and emerges hot, salty and rich in metals.

This salty water is dense, and forms pools of hot brine in the deepest areas of the sea, with unique forms of bacteria thriving in the water, which is toxic to nearly all other life forms. Several of the coastal countries have considered mining this water for its metals, but suitable technology is not yet available.
(Jo Gascoigne)