Unconformity at the Base of the Henrietta Group in Iowa

In Missouri the base of the Henrietta group is drawn at the base of the Lower Fort Scott limestone. This thin but persistent limestone is easily recognized in the field and can be identified in many well sections in northern Missouri and in Iowa. \u27While the Lower Fort Scott limestone may form the most practical boundary for the Henrietta in Iowa, it does not form the most natural lower limit of this group. After deposition of the Bevier coal and prior to the deposition of the Mulky coal there was a period of uplift and widespread channeling. Locally, as in Dallas and Guthrie Counties, numerous small faults cut beds of late Cherokee age and resting on these disturbed strata are sandstone and conglomerate which mark the beginning of Henrietta deposition