阿拉山口
Remarking on it as a geological and physical phenomenon, Carruthers continues:[T]he Dzungarian Gate is as unusual as that of the Jordan depression. They are both examples of a rift-valley caused by the movement of the earth's crust, not by the action of water. This valley once formed the connecting link between the drainage of Dzungaria and that of Southern Siberia. The chain of lakes at either end of the valley (Balkash, Ala Kul, Ebi Nor, etc.), are the remains of the great Asiatic Mediterranean Sea; if their waters were to rise a few hundred feet they would break through the Gate, flooding the plains to the north and south.