John Hewitt, age 11, of Jackson, Miss., for his question:

HOW DEEP IS THE MEDITERRANEAN SEA?

Since ancient times, the Mediterranean Sea has been one of the world's chief trade routes. Many early civilizations, including those of Egypt, Greece, Phoenicia and Rome, developed along its shores.

An underwater ridge between Sicily and Tunisia divides the Mediterranean into two basins. The eastern basin is deeper than the western one. The sea has an average depth of 4,926 feet. It reaches its greatest depth, 16,302 feet, in a depression called the Hellenic Trough that lies between Greece and Italy.

Land almost surrounds the Mediterranean Sea. Europe lies to the north, Asia to the east and Africa to the south. The Latin word "mediterranean" means "in the middle of land."

The Mediterranean covers about 969,100 square miles. The Black Sea, which many people consider part of the Mediterranean, has an area of about 196,100 square miles. Several other arms of the sea are also large enough to be called seas. They include the Adriatic, Aegean, Ionian and Tyrrhenian seas.

The Mediterranean is more than three times as long as it is wide. It has a maximum length of about 2,200 miles between the Strait of Gibralter and Iskenderun, Turkey. The widest part of the sea lies between Libya and Yugoslavia, a distance of about 600 miles.

You'll find that earthquakes occur frequently throughout the Mediterranean region, especially in Greece and western Turkey. Volcanic action forms many of the islands in the area. A few volcanoes in the region still erupt. They include Mount Etna, Stromboli and Vesuvius.

Scientists explain the earthquakes and volcanic activity by the theory of "plate tectonics." According to this theory, the earth's crust is made of about 20 rigid plates that are in slow, continuous motion. The two plates that carry the European and African continents are slowly but surely drifting toward each other. Their motion, the theory explains, stretches the earth's crust.

Many bays and inlets indent the coastline of the Mediterranean Sea.

Along most of the coast, rugged hills rise sharply from the water. Egypt and Libya have flatter coastal areas, with plains lying next to the sea.

Sicily, the largest island in the Mediterranean, covers 9,926 square miles. Other large islands include, in order of size, Sardinia, Cyprus, Corsica and Crete.

On the west, the Strait of Gibraltar connects the Mediterranean with the Atlantic Ocean. On the southeast, the Isthmus of Suez separates the Mediterranean and the Red Sea. The Suez Canal, a man made waterway, crosses this thin strip of land. Ships sail through the canal between the Mediterranean and the Red Sea and Indian Ocean.

The temperature at the surface of the Mediterranean averages about 61 degrees Fahrenheit. In summer, the surface temperature may reach 80 degrees and in winter it seldom drops below 40 degrees Fahrenheit