Final answer:
Sandstone is the predominant rock type in the Ogallala (High Plains) Aquifer, offering high porosity and permeability which is crucial for groundwater storage and extraction.
Step-by-step explanation:
The rock type that dominates the Ogallala Aquifer, also known as the High Plains Aquifer, is largely composed of sandstone. The aquifer material consists of sediments that were eroded from the Rocky Mountains, which include a significant portion of clastic materials such as sand and gravel. As these sediments tend to have higher porosity, the aquifer has a considerable ability to store groundwater.
The saturated thickness of the Ogallala Aquifer varies, with some areas reaching over 600 feet. When seeking to install a new water well, it is crucial to consider the depth to reach the aquifer and to identify layers with high porosity and permeability to ensure an adequate water supply.