Allowing the rigid lithosphere to move over a curved surface, spreading centers are linked to each other or to subduction zones by faults.

This statement seems to be describing the theory of plate tectonics, which explains how the Earth's crust, or lithosphere, is divided into large pieces called tectonic plates. These plates are rigid and move over the semi-fluid asthenosphere beneath them.

The movement of these plates is driven by convection currents in the mantle below the lithosphere. The heat from the Earth's core causes the material in the mantle to rise. As it cools, it then sinks back down, creating a circular current that pushes the tectonic plates above.

Spreading centers, also known as mid-ocean ridges, are places where tectonic plates are moving apart. This allows magma from the mantle to rise and form new crust. These are linked to each other or to subduction zones, where one tectonic plate is forced under another, by transform faults. These are places where tectonic plates slide past each other horizontally.

So, to summarize, the movement of the rigid lithosphere over a curved surface (the semi-fluid asthenosphere) allows for the creation of spreading centers, subduction zones, and transform faults, which are all linked to each other in the complex system of plate tectonics.