"The total thickness of the Trenton in the Prairie North is 475 feet according to Miller. This is about 175 feet thinner than at Trenton Falls. The Trenton thickens to the N.W. at the expense of the Utica. Miller gives the Utica a thickness of 180 feet. This is followed by 200 feet of similar Hard Shales with the same lithic fossils and is regarded by Miller as of Frankfort age. The dead layers are rare here. Then he calls the Lower Lorraine. The higher or Upper Lorraine is about 200 feet thick and becomes more and more a sandstone and is replete with fossils. Then follows the Onarga sandstone that is at least 100 feet thick."