The layer of soil and rock that is saturated with water is called a(n)

I think the answer is Aquifer. An aquifer is a body of saturated rock through which water can easily move. Aquifers must be both permeable and porous and include such rock types as sandstone, conglomerate, fractured limestone and unconsolidated sand and gravel. Fractured volcanic rocks such as columnar basalts also make good aquifers.
Geyser is a hot boiling spring of water that shoots steam and water into the air at times, so that's not it. Also it couldn't be tectonic plates because they are just earth's plates that move around. A well is a place to store water. Hope this helped