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We investigated the potential causes of topographic asymmetry at Gabilan Mesa, CA, a site that exhibits large aspect‐dependent differences in hillslope gradients and microclimates. Competing hypotheses have been proposed to explain the asymmetry observed at Gabilan Mesa. One hypothesis states that different microclimates on opposing slopes are responsible for differences in runoff or soil strength, which generates asymmetric topography. A second hypothesis states that differences in sediment flux from opposing slopes causes southward lateral channel migration and oversteepening of north facing slopes. To test these hypotheses, we carried out numerical modeling experiments, terrain analysis, and field measurements. We also considered the role of initial tilting in causing the asymmetry. We found that saturated hydraulic conductivity is considerably lower on south facing slopes in one highly asymmetric basin. This is consistent with the hypothesis that aspect‐dependent runoff is responsible for the asymmetry. We also used cosmogenic radionuclide‐derived erosion rates and topographic characteristics at Gabilan Mesa to test predictions from numerical landscape evolution models that incorporate asymmetry‐forming mechanisms. The aspect‐dependent models reproduce the erosional and topographic characteristics of Gabilan Mesa better than the lateral channel migration model. We conclude that aspect‐dependent runoff is the most likely explanation for most of the topographic asymmetry at Gabilan Mesa. Our results do not rule out tilting as a possible influence on the initial development of asymmetry nor do they rule out the possibility that lateral channel migration has contributed to the asymmetry, but we suggest that tilting and lateral channel migration are not primarily responsible for it.

 

Abstract The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 2,143 new measurements from 709 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. Particle properties and search limits are listed in Summary Tables. We give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, Probability and Statistics. Among the 120 reviews are many that are new or heavily revised, including a new review on Machine Learning, and one on Spectroscopy of Light Meson Resonances. The Review is divided into two volumes. Volume 1 includes the Summary Tables and 97 review articles. Volume 2 consists of the Particle Listings and contains also 23 reviews that address specific aspects of the data presented in the Listings. The complete Review (both volumes) is published online on the website of the Particle Data Group (pdg.lbl.gov) and in a journal. Volume 1 is available in print as the PDG Book. A Particle Physics Booklet with the Summary Tables and essential tables, figures, and equations from selected review articles is available in print, as a web version optimized for use on phones, and as an Android app. 

Abstract The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 3,324 new measurements from 878 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. Particle properties and search limits are listed in Summary Tables. We give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, Probability and Statistics. Among the 120 reviews are many that are new or heavily revised, including a new review on High Energy Soft QCD and Diffraction and one on the Determination of CKM Angles from B Hadrons. The Review is divided into two volumes. Volume 1 includes the Summary Tables and 98 review articles. Volume 2 consists of the Particle Listings and contains also 22 reviews that address specific aspects of the data presented in the Listings. The complete Review (both volumes) is published online on the website of the Particle Data Group (pdg.lbl.gov) and in a journal. Volume 1 is available in print as the PDG Book. A Particle Physics Booklet with the Summary Tables and essential tables, figures, and equations from selected review articles is available in print and as a web version optimized for use on phones as well as an Android app.