New subsurface data permit stratigraphic analysis of the Austin Group in northeast Texas. In the Dallas area thhis group is mainly chalk which grades eastward into two chalk tongues separated by a terrigenous clastic interval. The Ector Chalk Formation is the lower chalk unit; the Bonham Clay, Blossom Sandstone, and Brownstown Marl from the overlying clastic interval, and the Gober Chalk Formation is the upper chalk unit. The Ector Chalk Formation is considered to be lower Coniacian in central Texas. The Ector Chalk Formation is shown to be continuous across central and eastern Fannin County, Texas, which helps to define more precisely the geologic history of the Austin Group in northeast Texas.