An outstanding example of the control of oil and gas accumulation by sand distribution is provided by the Berea sand trend extending from Gay in Jackson County, northeastward through Spencer, Roane County, and Richardson, Calhoun County. With the exception of a few undeveloped edge areas, the productive area closely follows the extent of the sand. Cross sections indicate that the sand body originated as an offshore bar and the seaward side of the bar was on the southeast. The winding course of the bar is considered to be related to early structural movement. The presence of oil in only two of the three structurally low parts of the trend is interpreted as partially dating both the migration of oil and the formation of the structures. The truly synclinal accumulation of oi is described in detail and the comparative absence of water in the sand is discussed.

The secondary recovery of oil by means of a gas drive is being practiced with success in one oil field.

The sand trend extends approximately 60 miles northeast and southwest but only the southwestern 25 miles of the trend is discussed.