Differentiating Between Lithologic and Baselevel Controls on River Profiles: Canyons of the Colorado Plateau We propose a study of the relative roles of lithology and baselevel fall in canyon formation to better elucidate the role of lithologic heterogeneity in landscape evolution in general. To accomplish this we will study erosion patterns in and around deep canyons on the Colorado Plateau in relation to channel steepness patterns and rock properties. Important to our approach is the concept that the spatial structure of short-term erosion rates in disequilibrium landscapes like the Colorado Plateau reflects the longer-term temporal history of mainstem river incision. Not only do the canyons and surrounding landscapes of the Colorado Plateau provide an excellent natural laboratory for this investigation, but their study also carries significant broader impact and public education potential because of the iconic status of the Grand Canyon and the recent, high profile debate over the antiquity of this dramatic landform (age estimates range from<6 Ma to >60 Ma). Intellectual Merit Despite the fundamental, and long-recognized, importance of lithology in landscape evolution, it has received little attention in the quantitative studies of landscape evolution in recent decades. Partly this is because we have lacked the ability to quantitatively measure rock strength at the process scale and partly because until recently lacked firm theory to relate rock properties to river incision processes limitations that can now be overcome. We address three fundamental problems of broad interest to Geologists and Geomorphologists: (1) the role of lithology in river incision and landscape evolution in general, (2) how lithologic variability affects, and limits, our ability to interpret river incision history from study of landforms and (3) the controversial incision history of river canyons in the Colorado Plateau. The back drop to our study is the enigmatic Late Cenozoic exhumation history of the Colorado Plateau, but although our results should contribute to solving this long-standing problem, it is not our focus. We frame our study around three testable hypotheses concerning the fundamental controls on landscape evolution encoded in canyon landscapes and the last ~1 Myr of river incision history. Broader Impacts Given the icon nature of the Grand Canyon and the vast number of tourists that visit the canyon each year, public education is essential, especially when geoscience educators use National Parks as case studies for teaching exercises. As part of this research we will pursue a geoscience education study (part of the graduate students time commitment) of the effectiveness of using field analogs to teach about geologic process and landscape evolution, specifically related to canyon incision and relief generation. Folks living on reservation land on the Colorado Plateau are a key target audience. In addition to our public outreach efforts, the proposed study will provide significant training for one graduate student and several undergraduates. All students will interact with the PIs and institutions providing educational experiences for each student that are not typical. Specifically, this research will enhance the opportunities for undergraduates for direct involvement in cutting-edge research. We will proactively recruit women and underrepresented minorities.
|Effective start/end date||9/1/13 → 8/31/16|
- National Science Foundation (NSF): $115,893.00
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