The zone that acts as a resistance to the flow of ground water from an aquifer to the other aquifer is called as the aquitard. Aquiclude or aquifuge is a wholly impermeable aquitard that permits no ground water from between the aquifers.
In general, while the highly fractured rocks, gravel and sandy materials makes good aquifer, the clay, poorly settled sediments, and non-fractured rocks often forms aquitard.
We know that inside the Earth's crust there are two more layers, i.e., mantle and crust. In mantle, there are many molten rocks, they are in liquid like form. When this moves or <em>flow </em>then the continental plates move too.