Abstract

The Poth sands of the Upper Midway (Eocent) formation in Wilson County exhibit the identical high-constructive delta systems of the Lower Wilcox sections to the northeast, as reported by Dr. W. L. Fisher, Director, Bureau of Economic Geology, Austin, Texas.* It is suggested, but only after further investigation, that the time correlation of these southwestern depositional environments may place the start of the Wilcox cycle of deposition within or below the Poth sands, rather than in the accepted position at the base of the Wilcox transgressive sand series in these southwestern areas. The organically rich Midway shales have been reworked by the rivers and seas of the Lower Wilcox series, thus placing the paleontological evidence of formation demarkation at the presently accepted base of the Lower Wilcox massive sands in this up-dip facies.

Fortunately a number of wells have been drilled in the Hosek Field area of Wilson County which prove the existence of these distributary channels cutting through older formations which make up the local delta system of this area. The oil fields of these channel sand deposits are elongate on the dip and have oil columns, in some instances, of well over one-hundred feet from either the sand truncation or pinch-out to the oil-water contact.