In Kansas, three hydraulically connected but distinct aquifers: the Ogallala, Great Bend Prairie, and Equus Beds aquifers. In general, the Ogallala Formation is made up of unconsolidated sand, gravel, silt, and clay deposited by streams that flowed east from the Rocky Mountains during the Miocene Epoch. The Great Bend Prairie and Equus Beds aquifers are also composed of silt, clay, and gravel deposits left by streams flowing through central Kansas, but these deposits are generally younger (Pleistocene and Holocene) than the Ogallala. In some areas, these aquifers are in contact with each other and thus form one continuous aquifer.
The interval of geologic time between approximately 11,700 years ago and the present.
An irregularly or fantastically shaped column or pillar of rock left when surrounding sediment erodes.
Drilling that starts out vertical then gradually turns in a horizontal direction to extend a greater distance into an oil-producing zone.