Crust (geology) centers, where partial-melting of the underlying mantle yields basaltic magmas and new ocean crust forms. This "ridge push" is one of the driving forces of plate tectonics, and it is constantly creating new ocean crust. That means that old crust must be destroyed somewhere, so, opposite a spreading center, there is usually a subduction zone: a trench where an ocean plate is being shoved back into the mantle. This constant process of creating new ocean crust and destroying old ocean crust means that the oldest ocean crust on Earth today is only about 200 million years old. In contrast, the
The Conflict Over the Sovereignty of the Diaoyu Islands -- between Taiwan (ROC), China (PRC), & Japan depth of the Okinawa trough that locates in the east is as deep as 2,717 meters, forming a natural sea boundary with China and the Ryukyu islands. As the geological structure of the Ryukyu Islands belong to "oceanic crust", the Diaoyu Islands are "continental crust" that makes a significant difference in between those two. Also, the Diaoyu Islands has one of the largest scale of continental reef layer that contains an abundant amount of river deposits such as the Yangtze River and the Yellow River, and is therefore potentially rich in oil. The Diaoyu islands are considerably much more strategic