xvi, 136 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / This dissertation discusses the contribution of deep-seated landslides and earthflows to the morphology, erosion, and evolution of mountainous landscapes, focusing on the northern California Coast Ranges. In active landscapes, channel incision is necessary to create relief but also increases stresses in adjacent hillslopes, ultimately leading to slope failure. While conceptually simple, the spatial relationships between channel incision and landsliding have not been well quantified. Along the South Fork Eel River, I mapped the distribution of deep-seated landslides using light detection and ranging (LiDAR) derived maps. Landslide density increases in regions subject to late Pleistocene-Holocene channel incision and particularly in response to lateral incision at the apex of meander bends. Wavelet analysis of channel sinuosity reveals hillslopes are most sensitive to meander wavelengths of 1.5 km. Argillaceous lithology generates abundant earthflow activity along the main stem Eel River, yet spatial and temporal patterns of earthflow movement are poorly understood. I undertook a detailed study of the Kekawaka Earthflow using LiDAR, meteoric 10 Be in soil, orthorectified historical aerial photographs, and field surveys. Inventories of 10 Be in soil pits increase systematically downslope, indicate an average movement rate of 2.1 ± 1.3 m/a over the past 150 years, and establish a minimum earthflow age of 1700 years. The Kekawaka earthflow has a systematic history of movement, both spatially, with greatest movement in the narrow transport zone, and temporally, as velocities peaked in the 1960's and have slowed since 1981. I used LiDAR and aerial photographs to map earthflow movement and calculate sediment flux across 226 km 2 of the main stem Eel River. From 1944-2006, 7.3% of the study area was active, and earthflows account for an erosion rate of 0.53 ± 0.04 mm/a, over half the regional average sediment yield. Velocity time series on 17 earthflows suggest temporal earthflow behavior is influenced by decadal-scale changes in precipitation, temperature, and river discharge, although local topographic factors can overwhelm this climatic signal. When active, earthflows erode an order of magnitude faster than surrounding terrain; however, source supply limitations appear to govern long- term earthflow evolution. This dissertation includes previously published coauthored material. / Committee in charge: Joshua Roering, Chairperson, Geological Sciences; Ilya Bindeman, Member, Geological Sciences; Dean Livelybrooks, Member, Physics; Ray Weldon, Member, Geological Sciences; W. Andrew Marcus, Outside Member, Geography

xiv, 227 p. : ill. (some col.) A print copy of this title is available through the UO Libraries under the call numbers: KNIGHT QE720.2.K53 B75 2008 / The Holocene vegetation and fire history of the Klamath Mountains (KM), northern California, was reconstructed at three sites based on an analysis of pollen and high-resolution macroscopic charcoal in lake-sediment cores. These data were compared with five existing records to examine regional patterns. The objective was to determine the relative importance of climate history, substrate, and disturbance regime on the development of the Klamath vegetation. In the first study, two middle-elevation sites were compared along a moisture gradient in the northern KM. The pollen data indicated a similar vegetation history, beginning with subalpine parkland in the late-glacial period, and changing to open forest in the early Holocene and closed forest in the late Holocene. However, the timing of these changes differed between sites and is attributed to the relative importance of coastal influences and topography. The second study examined the effect of substrate and nutrient limitations on the vegetation history. The pollen data suggest that ultramafic substrates (UMS), containing heavy metals and low nutrients that limit plant growth, supported drier plant communities than those on non-ultramafic substrates (NUMS) for any given period. For example, between 14,000 and 11,000 cal yr BP, cooler and wetter conditions than present led to the establishment of a subalpine parkland of Pinus monticola and/or Pinus lambertina, Tsuga, Picea on non-ultramafic substrates (NUMS). On UMS, an open Pinus jeffreyi and/or Pinus contorta woodland developed. In the early Holocene, when conditions were warmer and drier than present, open forests of Pinus monticola/lambertina , Cupressaceae, Quercus and/or Amelanchier grew on NUMS, whereas open forest consisting of Pinus Jeffreyi/contorta , Cupressaceac and Quercus developed on UMS. In the late Holocene, cool wet conditions favored closed forests of Abies, Pseudotsuga , and Tsuga on NUMS, whereas Pinus jeffreyi/contorta , Cupressaceae and Quercus forest persisted with little change on UMS. The charcoal data indicate that past fire activity was similar at all sites, implying a strong climatic control. The results of both studies suggest that the influence of Holocene climate variations, disturbance regime, and substrate type have helped create the current mosaic of vegetation in the KM. / Adviser: Cathy Whitlock, Patrick Bartlein