Question

What are underground rock layers that store water called?

Answer 1

If groundwater is between two confined layers, it is called confined aquifer

Explanation:

If groundwater is not confined by an upper confining layer, it is unconfined equifer.

If, on the other hand, groundwater is confined by two confining units (such as upper confining layer and lower confining layer), it is called confined aquifer.

Below skecthes illustrate unconfined and confined aquifers (Reference: http://techalive.mtu.edu/meec/module04/Basics3.htm)