Final answer:
Circular patterns of heat transfer in the mantle are caused by convection, which is the movement of hot, less dense material rising towards the surface and cooler, denser material sinking towards the core. Convection cells and granulation patterns are examples of these circular heat transfer patterns.
Step-by-step explanation:
The circular patterns of heat transfer occurring in the mantle are a result of convection. Convection is the transfer of heat through the movement of a fluid, in this case, the mantle material. The hotter, less dense material rises towards the surface, while the cooler, denser material sinks towards the core. This continuous movement creates circular currents within the mantle.
An example of circular heat transfer patterns can be seen in convection cells, which are similar to circular patterns seen in boiling water or the granulation pattern on the Sun's surface. These circular patterns of convection drive plate tectonics, ultimately shaping Earth's surface.