Overview
- The paper, published August 17, 2026, argues that a continent‑scale “Great Escarpment of Laurentia” formed about 800–750 million years ago and drove long‑term erosion that brought deep crystalline basement rocks to the surface well before the Colorado River carved the modern canyon.
- Researchers led by Thomas Gernon used plate‑tectonic reconstructions and landscape‑evolution simulations to recreate a rift‑margin cliff roughly one kilometer high that retreated inland and stripped up to about eight kilometers of rock near the margin.
- The study presents a new mechanistic explanation for the Great Unconformity by linking variable amounts of missing rock across the southwestern U.S. to rift‑related uplift and prolonged escarpment erosion rather than a single uniform event.
- If the model is correct, the escarpment would have altered ancient river routes, sediment transport, and where seas flooded parts of Laurentia, reshaping the continent’s long‑term landscape and sedimentary record.
- The conclusions are model based and generate clear, testable predictions for thermochronology, stratigraphic correlation, and field mapping that geologists will need to confirm before the hypothesis becomes widely accepted.