FIGURE 3 in Telychian (Llandovery, Silurian) conodonts from the LaPorte City Formation of eastern Iowa, USA (East-Central Iowa Basin) and their implications for global Telychian conodont biostratigraphic correlation

FIGURE 3. Cross section of Silurian strata in eastern Iowa. The lower two members of the Hopkinton Formation become indistinguishable in the western part of the cross section. The Sweeney and Marcus members are referred to as Hopkinton A, the Farmers Creek Quarry Member as Hopkinton B, and the Picture Rock Member as Hopkinton C in this manuscript. Note the change in datum at the CC core in Linn County. Modified from Witzke (1992, figure 6).