Modern bedrock streams and rivers emerged in the Midwestern United States in response to glacial outwash floods ~19,000 years ago and continued to adjust to new drainage patterns over the landscape formed by Wisconsin glaciation events. The Illinois River and corresponding tributaries form a fascinating landscape with canyons carved 50-200 m deep into the St. Peter Sandstone. These geomorphic features are preserved and open to visitors as Starved Rock State Park in Central Illinois. Free access to the state parks and close proximity to the large Chicago metropolitan area result in frequent visitation to this natural attraction. Recently, the rates of natural stream incision appear to be overprinted by direct human influences on the landscape. The St. Peter Sandstone is a weakly cemented, extremely friable quartz arenite, making it susceptible to human disturbance and rapid natural erosion. This study explores how quickly present day changes occur along bedrock surfaces using photogrammetric Structure-from-Motion (SfM). Repeat photographic data were collected once per month from two sites within the park where canyon walls contained human carvings that served as reference features to align photos and monitor change. Photos were merged in Agisoft PhotoScan Pro to construct 3D point clouds and imported into CloudCompare to measure changes to rock surfaces between monthly visits. The photogrammetric SfM analysis detected measurable change on a centimeter to millimeter scale. Changes along footpaths were observed when visitor traffic was high. During winter months when visitor traffic decreased, rainfall and snowmelt runoff primarily caused mobilization and removal of loose sediments covering bedrock surfaces. Bedrock thin sections from each site were studied to assess the influence of cement on erosion rates. Lower cement concentrations were observed at the outcrop site with the greatest measured surface change. Changes detected with SfM analyses demonstrate that human interactions can influence erosion processes in a short time. While both natural and human caused changes occurred on bedrock surfaces, precipitation created greater measurable differences.