Abstract
The sub-Absaroka unconformity in the U.S. Eastern Interior basin is characterized by a series of entrenched paleovalleys. Structural control of the paleovalleys resulting from the reactivation of basement features in the southeastern part of the basin is indicated by (1) parallelism of paleovalleys to faulting, (2) diversions of paleovalley trends corresponding to fault intersections, (3) facies changes in paleovalley-fill deposits and paleovalley geometry across fault blocks, (4) near-rectangular paleodrainage patterns, (5) channeling on horsts, (6) paleocurrents parallel to faulting, (7) diversion of a paleovalley against paleoslope and parallel to the strike of the Webster syncline, and (8) paleocolluvial and paleoslump deposits along fault-bounded valley walls.