Late Quaternary glaciation of south-central New York State generated accumulations of sediment in Tompkins County which are still unconsolidated, now mostly hidden beneath forests, fields, and towns. Elevations of the contact between unconsolidated sediment and Devonian bedrock imply that the ancestral position of Fall Creek valley west of 76.43° longitude, prior to Quaternary glaciation, trended west-southwest across what is now the plain between modern Fall Creek and Cascadilla Creek valleys. The fill of ancestral Fall Creek Valley records a complex mosaic of sediments accumulated under time-variable and spatially variable conditions. At five locations along the north wall of Fall Creek valley west of 76.433°W longitude and at two boreholes south of Fall Creek Valley, details of the texture, fabric, and bed architectures underpin interpretations of environmental conditions during deposition. This manuscript is a field guide to those sediments, which range in thickness from 25 m (80 ft) to 60 m (200 ft) overlying Devonian rock, and are either contemporaneous with the last widespread glacial cover of this area, the Valley Heads readvance, or predate the Valley Heads readvance. Through the 2.5 km (8200 ft) long sector of modern Fall Creek Valley reported here, a till that is attributed to the Valley Heads ice readvance occupies the upper valley wall. At the westernmost valley-wall section, about 30 m of sediment include a basal till and an uppermost Valley Heads till, between which sand deposits dominate with several meters of interbedded gray muds. The sands and muds were deposited from water with high degrees of suspended sediment load, potentially in a set of small proglacial lakes or pools at the front of a retreating glacier. At the Varna High Bank, three units record distinct environmental conditions. Below the 20-m-thick Valley Heads till, a 15-m-thick unit of sands and gravels was deposited by stream flow, with an upper interval made of a laterally continuous gravel distinguished by foreset beds to 10-m-height that record the merger of a stream into a deep pool or lake. Below a contact that is interpreted as a comparatively long-lived depositional lacuna, the basal 5-m-thick brown gravel also likely formed by stream flow. At the easternmost valley-wall section analyzed, three major units of differing depositional conditions again crop out. Valley Heads till caps the section, below which occur well stratified silty sands and well sorted gravels, in turn overlying a basal clay with floating cobble clasts that lacks internal organization. In the middle unit, the sands were deposited rapidly from flowing water with a high load of suspended sediment, and the gravel is interpreted to be glacial outwash. The basal clay and cobble unit probably reflects a sequence of two environmental conditions, first lacustrine deposition and then overriding by a glacier. At these three Fall Creek locations, the lower two units differ from those at their lateral neighbors, which is interpreted to mark a high degree of lateral variation of post-depositional preservation. The two boreholes, roughly 1.2 km and 1.3 km south of the westernmost valley wall exposures, penetrate unconsolidated sediment over Devonian bedrock that is similar in thickness (24 m) to more than twice as thick (60 m) as the Fall Creek valley Quaternary sediments. In both, a surficial till that is inferred to be Valley Heads is underlain by a 5-m-thick unit of very well laminated silty clay interpreted to be lacustrine. In both boreholes the next underlying unit is a matrix-rich till that persists to bedrock in one and to at least 30 m subsurface in the other. The nature of the remaining nearly 30-m-thick unit in the borehole where bedrock is deeper is poorly documented, including both gravels and sands, some subrounded to rounded, suggesting that the stack of sediments records important shifts of depositional conditions.