Geochronological Data for: Age and recurrence of paleoseismic surface faulting at the Dry Canyon trench site, northern Red Rock fault, Red Rock Valley, southwestern Montana

Prominent scarps across alluvial fans along the northeast Tendoy Mountains in southwest Montana are evidence of late Quaternary surface ruptures on the 34 km-long Red Rock fault. Previous evaluations of the fault scarp characteristics, the distribution and ages of hanging wall alluvial fans, and the attributes of footwall drainage basins led to subdivision of the Red Rock fault into two or three segments and to the suggestion that surface ruptures may be older on the northern part of the Red Rock fault. We excavated a paleoseismic trench across a 5 m-high scarp at Dry Canyon, about 17 km north of Little Sheep Creek, to evaluate the number and timing of surface ruptures on the northern part of the fault. We interpret two, or possibly three, late Pleistocene and Holocene surface ruptures based on stratigraphic and structural interpretations and five optically stimulated luminescence ages.