Tectonic events at the intersection between the Hope fault and the Purcell Trench, northern Idaho the right-lateral Hope Fault was active intermittently from Precambrian to Eocene whereas the Purcell Trench is a Late Cretaceous graben - Harrison, Jack E.; Kleinkopf, Merlin Dean; Obradovich, John D. (US Gov. Print. Off., 1972)