For 10 points, name these underground rock layers that contain water.
Unconfined structures of this type occur when they terminate at the phreatic surface, while confined ones lie below an impermeable layer. A flow equation in these structures can be solved using the MODFLOW computer program, and is also governed by Darcy's law, which is dependent on porosity. These entities consist of permeable rock below the water table, and artesian wells are drilled into them. For 10 points, name these underground rock layers that contain water.
Unconfined structures of this type occur when they terminate at the phreatic surface, while confined ones lie below an impermeable layer.
{aquifers}