Much of the ground is actually saturated with water. A. Sediments that hold water were spread by glaciers and are still spread by rivers and streams. B. Water is stored underground in beds of loose sand and gravel or in cemented sediment. C. The size of a saturated rock's pores determines how much water it will retain when the rock is put in a dry place. D. Groundwater often remains underground for a long time before it emerges again. E. Like sandstone, basalt is a crystalline rock that is very porous. F. Beds of unconsolidated sediments are typically located at inland sites that were once underwater.