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The Mystery Of the Rising Caspian

Few seas rise and fall as mysteriously and unpredictably as the Caspian.

This sea is a peanut-shaped body of water more than 700 miles from top to bottom and about 170 miles across - close to the size of California. Its eastern shores are the deserts and steppes of Central Asia. Its western banks lead up to the august Caucasus Mountains. The Ural River, which flows into the upper right corner of the Caspian, neatly divides Europe and Asia.

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The Caspian is fed primarily by the mighty Volga River, which winds its way out of European Russia and enters the sea as a sprawling, hundred-mile-wide web of delta channels. The only way water leaves the sea is through evaporation. It is saltwater, but only about one-third the salinity of the oceans.

In prehistoric times, the Caspian was probably bigger, connected to other seas like the Baltic and the Black. It was also so small at one point that the Volga entered it down near present-day Baku, which lies at what is now the sea's midpoint.

Early this century, the level of the Caspian began to drop. By the early 1970s, it had dropped by about 12 feet. Soviet engineers blocked off the Caspian's largest evaporation pan, a shallow bay extending into the Turkmenistan desert for thousands of square miles. They thought about more radical steps, such as diverting Siberian rivers into Central Asia.

It's a good thing they didn't. In about 1977, the Caspian mysteriously started to rise again. Now the sea is back to the level of about 1930. Loading docks in Turkmenbashi, Turkmenistan, are under water. Pieces of walls and foundations break the surface off the beach at Derbent, Russia. Near Astrakhan, 30 villages have been moved.

No one knows for sure why the Caspian is rising or when it will stop. One theory is that tectonic shifts of the sea floor are raising the water level. Another is that oil films covering parts of the Caspian surface have cut evaporation. Vladimir Ivanov, director of the Caspian Fisheries Research Institute, sees a more likely answer in the weather patterns. Russia has had wetter weather than usual over the past 20 years.

If the sea keeps rising, there is a risk now that water will hit radioactive soils from the days when the Soviets tested nuclear bombs underground and reportedly used them as primitive earth-moving tools near the shore. But so far, the Caspian is cleaner than it has been in years. Hard times in the Russian economy mean the great factories up the rivers have fallen idle.