Meander Canyon cuts down through the lower Colorado Plateau stratigraphy beneath the Island in the Sky mesa, exposing the Cedar Mesa Sandstone, Organ Rock Shale, and White Rim layers that build Canyonlands' architecture. The meanders are entrenched and ancient: the river established this winding course before the land uplifted, then cut downward as the plateau rose, leaving walls that climb hundreds of feet above sandy beaches. The river is older than the uplift, and the canyon is the proof. The corridor enters Canyonlands National Park at river mile 31, with the only real gradient break coming far below at The Slide Rapid near mile 1.5, just above the Confluence.
Meander Canyon cuts through the lower stratigraphy of the Colorado Plateau, exposing the Cedar Mesa Sandstone and White Rim layers that define Canyonlands' architecture. The entrenched meanders are ancient — the river established its course before the land uplifted, and has since cut downward to create the dramatic canyon walls that now rise hundreds of feet above the waterline. In the authoritative geologic/guidebook framing, Meander Canyon extends upstream from Potash another ~17 miles through The Portal at the Moab Valley escarpment — Desert Maritime tracks that upstream reach as the separate 'The Portal' section for navigation and climbing-resource clarity while preserving the ~61.5 mi total geologic extent note here. The corridor crosses into Canyonlands National Park at river mile 31; below the boundary, 44 river miles run inside the park before reaching the Confluence.