1. New constraints on the integration of the Bear River and cutting of Oneida Narrows --implications for the Bonneville record Joel Pederson and Jesse King

2. problem -Bonneville record important, and radical recent evolution of the Bear River controls the hydrologic balance photo: Eric Beard modified from Link et al., 1998 field guide -Importance long recognized (Bright, 1963), but not widely, and needs better constraints (Kaufmann and students) -Here we add additional data and analyses, making for a tight story with more nuanced implications

3. Thatcher Basin Oneida Narrows Cache Valley

4. This study so far: mapping, OSL, terrain reconstruction

5. Results

8. Key relations in Thatcher Basin

15. Oneida-Bear River OSL geochronology

16. Results 25.6 +/- 2.7 ka 19.7 +/- 1.9 ka

17. Summary in long profile

18. Takehome points -Bear River integration now better constrained at ~52 ka, spillover point at Oneida Dam -Integration initiated 200+m of canyon cutting before Bonneville highstand, 1 cm/yr averaged! -Shift in hydrologic balance very likely accounts for anomalous Bonneville highstand and outburst flood