The Bloomsburg is an ancient delta system carrying sediment westward from the Taconic Highlands slowly filling the basin.

Each unit has a lower division of evaporite (salt or anhydrite) and the upper section is a carbonate, typically dolomite.

In the central part of theses states on east in is the lowest member of the Wills Creak.

In the East or Wills Creak area, the Middle Vernon has occasional red shales, particularly in the southeast.

The base of the Middle Vernon is marked in the Salina by the last salt bed, and a slight overall rise in gamma.

The base is marked by a sharp drop in gamma, due to a salt bed in the west and dolomite to the east.