Rapid formation of a modern bedrock canyon by a single flood event

Deep river canyons are thought to form slowly over geological time (see, for example, ref. 1), cut by moderate flows that reoccur every few years. In contrast, some of the most spectacular canyons on Earth and Mars were probably carved rapidly during ancient megaflood events. Quantification of the flood discharge, duration and erosion mechanics that operated during such events is hampered because we lack modern analogues. Canyon Lake Gorge, Texas, was carved in 2002 during a single catastrophic flood. The event offers a rare opportunity to analyse canyon formation and test palaeo-hydraulic-reconstruction techniques under known topographic and hydraulic conditions. Here we use digital topographic models and visible/near-infrared aerial images from before and after the flood, discharge measured during the event, field measurements and sediment-transport modelling to show that the flood moved metre-sized boulders, excavated ~7 m of limestone and transformed a soil-mantled valley into a bedrock canyon in just ~3 days. We find that canyon morphology is strongly dependent on rock type: plucking of limestone blocks produced waterfalls, inner channels and bedrock strath terraces, whereas abrasion of cemented alluvium sculpted walls, plunge pools and streamlined islands. Canyon formation was so rapid that erosion might have been limited by the ability of the flow to transport sediment. We suggest that our results might improve hydraulic reconstructions of similar megafloods on Earth and Mars

Submicron Structures Fabrication and Research

Contains reports on thirteen research projects.Joint Services Electronics Program (Contract DAAG29-83-K-0003)U.S. Navy - Office of Naval Research (Contract N00014-79-C-0908)National Science Foundation (Grant ECS82-05701)I.B.M. (PO No. 90305-QPSA-559)U.S. Department of Energy (Contract DE-AC02-82-ER13019)Lawrence Livermore Laboratory (Contract 2069209

Nanostructures Technology, Research, and Applications

Contains reports on seventeen research projects and a list of publications.Joint Services Electronics Program Contract DAAL03-92-C-0001Joint Services Electronics Program Grant DAAH04-95-1-0038Semiconductor Research Corporation Contract 94-MJ-550National Science Foundation Grant ECS 94-07078U.S. Army Research Office Contract DAAL03-92-G-0291Advanced Research Projects Agency/Naval Air Systems Command Contract N00019-92-K-0021National Aeronautics and Space Administration Contract NAS8-36748National Aeronautics and Space Administration Grant NAGW-2003IBM Corporation Contract 1622U.S. Army Research Office Grant DAAH04-94-G-0377U.S. Air Force - Office of Scientific Research Grant F-49-620-92-J-006

Epitaxial Growth and Processing of Compound Semiconductors

Contains an introduction and reports on six research projects.Defense Advanced Research Projects Agency/U.S. Navy - Office of Naval Research University Research Initiative Subcontract N00014-92-J-1893Joint Services Electronics Program Grant DAAH04-95-1-0038National Center for Integrated Photonics Technology Contract 542-381National Science Foundation Grant DMR 92-02957MIT Lincoln Laboratory Contract BX-6085National Center for Integrated Photonics Technology Subcontract 542-383U.S. Air Force - Office of Scientific Research Grant F49620-96-1-0126U.S. Navy - Office of Naval Research Grant N00014-91-J-1956National Science Foundation Grant DMR 94-0033

Submicron and Nanometer Structures Technology and Research

Contains reports on sixteen research projects and a list of publications.Joint Services Electronics Program Contract DAAL03-89-C-0001Joint Services Electronics Program Contract DAAL03-92-C-0001National Science Foundation Grant ECS 90-16437Semiconductor Research Corporation Contract 90-SP-080U.S. Navy - Naval Research Laboratory Contract N00014-90-K-2018IBM CorporationU.S. Air Force - Office of Scientific Research Grant F49620-92-J-0064National Science Foundation Grant DMR 87-19217National Science Foundation Grant DMR 90-22933National Aeronautics and Space Administration Contract NAS8-36748National Aeronautics and Space Administration Grant NAGW-2003National Science Foundation Grant DMR 90-01698Spire Corporatio

Nanostructures Technology, Research, and Applications

Contains reports on twenty research projects and a list of publications.Joint Services Electronics Program Contract DAAL03-92-C-0001Semiconductor Research Corporation Contract 94-MJ-550U.S. Army Research Office Grant DAAL03-92-G-0291Advanced Research Projects Agency/Naval Air Systems Command Contract N00019-92-K-0021National Science Foundation Grant ECS 90-16437National Science Foundation Grant ECS 90-16737IBM Corporation Contract 1622U.S. Air Force - Office of Scientific Research Grant F-49-62-92-J-0064National Science Foundation Grant DMR 87-19217National Science Foundation Grant DMR 90-22933National Aeronautics and Space Administration Contract NAS8-3674