The discovery and confirmation of Lava Creek B (LCB) ash localities and river gravel outcrops near Black Canyon of the Gunnison National Park suggest the presence of a Quaternary paleovalley. The geometry of this paleovalley was contrasted to modern valleys to infer incision rates and the nature of the basinís change since the deposition of the LCB ash at about 640,000 years ago. The LCB ash age constrains the maximum incision rate to an average of 64 cm/ky. This suggests that up to 74%, or 410 meters, of the Black Canyon of the Gunnison has incised in the last 640 ky. These incision rates are much higher than those found in other areas of the Western U.S., and suggest that high incision rates in the Rocky Mountains may be local phenomena rather than the product of large scale climate change or neotectonics.
|Presenter:||Bryan Kaproth (Undergraduate Student)|
|Time:||9:45 am (Session I)|