Syndepositional features, interpreted as paleoseismites indicative of six late Quaternary surface ruptures, were exposed in a trench across the Lima Reservoir fault in the Centennial Valley of southwestern Montana. Younger events progressively displaced four loess deposits capped by paleosol, and overstepping unconformities. Older events are marked by paleo-sandblow vents, ejected sand, and a deformed stream-channel deposit. Fossils of horse (Equus) and northern pocket gopher (Thomomys talpoides), place a 120-10 ka range on the oldest event. Stratigraphy and soils suggest that it occurred during the last Pinedale interstade (ca. 20 ka).Line-length balancing and progressive retro-deformation of faults show that > 8.8 m of cumulative fault displacement with ~2 m of horizontal extension occurred since then. Orientation of faults, clastic dikes, and slip vectors, along with earthquake focal mechanism solutions, were used to determine stress-field orientations for the six events. Normal faulting associated with northeast-southwest Basin and Range extension produced three events with 4.7 m offset, a displacement rate of ~23.5 cm/k.y., and a recurrence interval of 6.7 k.y. Oblique-reverse faulting associated with east-northeast-west-southwest compression produced two events with 3.7 m offset, clastic dike injection along joints or joint-reactivated faults in arched areas above the oblique-reverse faults, a displacement rate of 18.5 cm/k.y., and a recurrence interval of ~10 k.y. Reverse faulting, associated with northsouth compression, produced clastic dike injection during one event with 0.4 m offset, a displacement rate of <2 cm/k.y., and a recurrence interval of >20 k.y. Bartholomew, M.J., Stickney, M.C., Wilde, E.M., and Dundas, R.G., 2002, Late Quaternary paleoseismites: Syndepositional features and section restoration used to indicate paleoseismicity and stress-field orientations during faulting along the main Lima Reservoir fault, southwestern Montana, in Ettensohn, F.R., Rast, N., and Brett, C.E., eds.,
