We document late Pleistocene--Holocene aggradation and incision processes at the mountain front of the Qilian Shan, an active intracontinental fold-and-thrust belt accommodating a significant portion of the India-Asia convergence. The Shiyou River cuts through a NNE vergent fault propagation fold with Miocene red beds in the core and Pliocene--Quaternary growth strata on the northern forelimb. South of the anticline, Miocene strata dip 20¿ SSW, suggesting a similar orientation for the basal d¿collement. After aggradation of an ~150-m-thick, late Pleistocene valley fill, the Shiyou River formed three terraces. The highest terrace, located 170 m above the river, constitutes the top of the fill. The other terraces are fill cut terraces: their treads are located 130--105 m and 37 m above the river, respectively. The 10Be exposure dating of the terraces suggests that river incision accelerated from 0.8 ¿ 0.2 mm yr-1 to ~10 mm yr-1 at 10--15 kyr. We interpret fast Holocene river incision as largely unrelated to tectonic forcing. The late Pleistocene incision rate of 0.8 ¿ 0.2 mm yr-1 places an upper limit of 2.2 ¿ 0.5 mm yr-1 on the horizontal shortening rate, assuming that incision is solely caused by rock uplift above a d¿collement dipping 20¿. However, the actual shortening rate may lie between ~2.2 mm yr-1 and zero because deformation of the terraces and the valley fill cannot be unequivocally demonstrated. Our estimate is consistent with the bulk shortening rate of ~5--10 mm yr-1 across several faults in NE Tibet derived from neotectonic and GPS data, although in case of the Shiyou River, Holocene deformation is barely discernible owing to intense climate-induced river incision.