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
Core-and-pod kind of large and wide tree, with many “branches,” or pods, off the main “trunk,” or core. Core-and-pod Core-and-pod design is a network design that uses individual pods that hang off the core layer as atomic units. Within the pod, there may be only a single access layer or a “leaf and spine” network in the pod. The routed core layer serves as a fast and simple way to connect many generations of pods to each other. When the “leaf and spine” network is used within the pod, the core layer can be referred to as the “spine of spines,”