Many landscape evolution models have considered the interaction of exogenic and endogenic processes. However, geomorphological processes have not been successfully incorporated in landscape evolution models. The thesis begins with a critical analysis of methodologies for the study of large-scale geomorphological processes. A framework based on a generalization of the relevant processes is recommended. Hillslope and channel submodels, which are based on typical processes operating in coastal regions of British Columbia, are introduced. The following hillslope processes are considered: (i) slow, quasi-continuous mass movements; (ii) fast, episodic mass movements; and (iii) weathering. The transport relation for fast, episodic mass movements was found to be nonlinear. Fluvial transport in both low and high-gradient channels and debris flow transport are considered in the channel submodel. A bed load transport equation, which is a revised version of the Bagnold stream power formula, is derived. Suspended load is calculated using a suspended load/contributing area correlation. Connections between hillslope and channel processes are considered to ensure adequate representation in the model. The hillslope and channel submodels are explored in one-dimensional and surface model runs for small drainage basins in the Queen Charlotte Islands, British Columbia. Tests of the fluvial submodel demonstrate the robustness of the bed load equation used in this study. A conceptualization of the landscape into unstable and stable regimes is introduced. Results of surface model runs emphasize the key role of low-order channels in transferring sediment from hillslopes to main channels. The exercise of constructing and running the model highlighted major gaps in our present understanding of geomorphological process operation and sediment routing. Suggestions for future research are extensive and are outlined in the concluding chapter of the thesis.

<p> Light detection and ranging (LiDAR) data and field observations were used to create a new tectonogeomorphic strip map along the San Andreas Fault from Wrightwood 47 km southeast to Highland. Three hundred and thirty one geomorphic features were identified and the displacements of 23 offset and deflected streams were measured using Quick Terrain Modeler (QTM). Offsets cluster around 10-50 m, and only one offset is smaller than 5 m, and a few larger offsets (100 m-200 m). </p><p> The primary purpose of this project, besides creating the strip map, was to determine how slip is transferred between the northern San Jacinto fault and Mojave-San Bernardino segments in the Cajon Pass area. Previously published slip rate data suggests slip transfer from the San Jacinto fault to the San Andreas fault between Badger Canyon and Cajon Creek at Cajon Pass area. However, there are no significant changes in offset amounts along the northern end of the San Bernardino segment, and the most likely location for slip transfer would be Cajon Pass.</p>

<p> Eight dissolution caves from the Helderberg Plateau in Schoharie County, New York were studied to investigate unusual sediment packages previously interpreted to be deposits laid down during stagnant ice-cover conditions of the Wisconsin glaciation. The sediment package, consisting of white finely laminated silts and clays are overlain by coarse gravels, in turn overlain by dark silts and clays. Analysis of 63 sediment samples was inconclusive in terms of organic content, but indicated a higher degree of fine-grained calcite material in the white clays than in the overlying units. The caves with the white clays exist only within the footprint of Glacial Lake Schoharie, with lower elevation caves containing a thicker white clay sequence, a measure of the duration of lake cover. The sediment sequence represents glacial rock flour formed under stagnant lake conditions, overlain by outwash deposits emplaced during lake termination, and more recent sediment from soil-loss deposition.</p>

<p> Recharge areas for most springs are rarely known because they can be sourced from proximal, shallow, atmospheric sources or long-travelled, deep, regional aquifers and alteration along the flow path is common. Stable isotopic (¹⁸O and ²H) geochemistry of springs water can provide indications of relative flow path distance. Locally sourced springs generally have an isotopic signature similar to the isotopic values of local precipitation for that region and elevation. Springs with a different isotopic composition than local meteoric inputs likely have non-local recharge, representing a regional source. Exceptions to this rule include springs in karst terrain, geothermal locations, or travertine-rich groundwater systems, where other physical or geochemical processes influence the isotopic signature of the water. In this study, we tested local vs. regional sourcing using springs isotopic data from regional studies across Western North America in Arizona, Nevada, and Alberta. These regional study sites included the Basin and Range, Transition Zone, Colorado Plateau, Cordillera, Interior Plains physiographic regions, and lowland to montane aquifers. The combination of location-specific physical data with stable isotopic groundwater data provides an effective method for flow path determination at springs with similar flow and chemistry. Springs from Arizona were found to be a mix of regional and local recharge, those from Nevada were locally sourced, and Alberta's springs are generally sourced from regional flow systems. </p><p> Springs provide a truly unique ecosystem where groundwater first daylights, mixes with surface waters, and both plants and animals find refuge. Variability of springs type (the springs geomorphic properties) can have profound effects on all aspects of a groundwater spring. Water chemistry may exert significant changes on vegetation, which in turn modify the springs ecology. Changes in vegetation composition and density can also change erosion rates and channel morphology, thereby altering geomorphology. Analyses of data from southern Nevada and Alberta, Canada housed in an extensive springs database of western North America were interpreted to determine the interconnectedness of geochemistry, geomorphology, and vegetation cover. Using various statistical techniques, the opposite variables were significant in the two field areas. In the Spring Mountains the highest elevation clusters had the highest plant species diversity and the fewest spheres of discharge. In Alberta the clusters with average elevation, neither highest nor lowest, were the groups with the highest plant species diversity and most variability in geomorphic surface types.</p>

<p> A two-part study was conducted on the evolution of the shoreline of the Charles River basin on a city-wide scale as well as in finer detail in Magazine Beach Park, along the Cambridge shore of the river. Both parts of the study utilized geographic information technology (GIT) to integrate and analyze data from modern and historical sources, including maps, digital elevation models (DEMs), and orthographic and oblique photography. The city-scale portion of the study produced estimates of the total area of new land made within the study area since Boston's founding in 1630, 14.3 km², of which 6.5 km² was added in the Back Bay area alone. Efforts were also made to quantify the total volume of new land added using the 2002 MassGIS DEM, but that estimate, 30 million m³, was based on somewhat speculative estimates of the original mudflat and salt marsh elevations and is a less robust estimate than those of the surface area. </p><p> The GIT was also used to display the integrated spatial data in both 2D (map or orthographic view) and 3D (oblique view) to facilitate visualization of historical landscape changes. This technology was also used to produce a 3D time series of landmaking by vertically extruding historical map-based polygon layers in proportion to the length of time between successive layers. This presented a unique opportunity to depict what would normally be shown as a 2D graph of area vs. time instead as a graphic that shows area and time but also shoreline shape at several points in history, thus providing a more full picture of how the basin evolved over time. </p><p> In addition, the study of Magazine Beach Park centered around a survey-scale 500 MHz ground-penetrating radar exploration of the entire park, which yielded some clues about the park's stratigraphy and recent anthropogenic changes, including the location and extent of the former beach that used to extend half the length of the park. However, the wide spacing of the GPR survey lines and high level of sediment disturbance and fill in some parts of the park limited the success of the survey.</p>

No description available.

<p> Wildfires dramatically affect hydrologic processes including runoff and erosion, which in turn can impact society. Disturbance by fire creates ecosystem heterogeneity, prompting many species to adapt to fire cycles. Human impacts have altered fire frequency and affected natural systems to the point that additional landscape-scale disturbances may cause a disruption in ecosystem form and function. The altered ecosystems and increased development in forests may exacerbate post-fire impacts, affecting more of the population in fire-prone regions. </p><p> The following three studies will improve our understanding and management of post-fire impacts on stream channel processes. A catchment in eastern Arizona where runoff data were collected between 1962 and 1983 was subsequently burned by a wildfire in 2011. The direct comparison of pre and post-fire runoff showed that the fire made runoff more rapid, increased peak discharge rates, and compressed the time scale of storm hydrographs. These results can help improve post-fire runoff modeling and management efforts. </p><p> The second topic addressed the scaling of sediment delivery across hillslope and small catchment scales. Erosion data used in this study were from the Arizona site and five other sites across the western US. Results from five of the six sites showed that sediment delivery significantly decreased with increasing spatial extent, while the lack of trend at the sixth site illustrates the variability in erosion responses across ecosystems. The relationships developed in this study will help improve estimates of sediment delivery rates at the small-catchment scale using more easily acquired data from small plots. </p><p> The third study addressed whether straw bale check dams reduce post-fire sediment yields or affect ephemeral stream channel morphology. A series of laboratory flume experiments based on measured post-fire field conditions showed that check dams can store sediment from initial runoff events, but that a large number of check dams would be needed to reduce post-fire sediment yields. The stored sediment reduced the local channel gradient, but the check dams did not otherwise affect the channel morphology. These data and field observations were used to develop a check dam classification system that can be applied in ephemeral streams in burned or unburned areas.</p>

No description available.

<p> Significant accumulations of lower Wilcox Group coals have previously been reported throughout regional reconnaissance studies in north-central Louisiana. The present study is part of a series of contiguous sub-regional studies that incorporate much higher well densities, evaluate each well log individually for coal presence, and map the structures and thicknesses of the Reynolds and the Russell coal. The thickest coal accumulations are found in paralic lagoon deposits in the northern portions of the study area within Lasalle and Rapides Parishes just south of the Angelina-Caldwell Flexure and ontop of the LaSalle Arch. No lower Wilcox Group coals were found south of Township 2N (latitude 31.100&deg; N) in this study. Lower Wilcox Group strata south of Township 2N are interpreted as a shoreline with marine conditions to the south, not suitable for coal accumulation.</p>

<p> The objective of this research was to determine the size, shape, activity of dunes, petrological characteristics, and provenance of sand in the Winnemucca Dune Complex (WDC). Methods and procedures included the extraction of weather records from meteorological stations, generating surficial landform maps, measuring dune advancement from historical aerial imagery, and field sampling of sand for laboratory inspection of grain size and mineralogical composition. Grain size parameters and textural classification of dune sand were determined using a Laser Granulometer and GRADISTAT v.8 (Blott &amp; Pye 2001). The mineralogical composition and physical classification of dune sand was analyzed using fine powder X-ray Diffractometry and stained standard thin sections. Results were plotted on ternary diagrams with Quartz-Feldspar-Lithic (Folk 1974) and Quartz-Alkali feldspar-Plagioclase (Streckeisen 1976, 1978) overlays. </p><p> Measurements from surficial landform maps estimate wind-blown deposits are distributed on 472.2 square kilometers of terrain. Active dunes are universally dominated by unique configurations of intermediate shaped barchan and parabolic dunes. For the purpose of this study these features were termed as barchanbolic. WDC is primarily covered by 6 crescentic complexes, 1 large sand sheet, and discontinuous sets of compound barchanbolic-parabolic dune fields. The crescentic complexes are composed of closely spaced barchanoidal and transverse ridges with occasional star dunes. Between the complexes are repetitive sequences of compound and individual barchanbolic-parabolic dunes that laterally radiate towards the bounding perimeter of WDC. Sand sheets, ramps, climbing, descending, cliff-top, and lee dunes are also present along mountain crests and hillsides. Sand sheets (56.3 square kilometers) and active dunes (162 square kilometers) extend across 218.3 square kilometers which constitutes 46.2% of the wind-blown deposits in WDC. Since the year 1980 sand dunes have been advancing at maximum rates from 1.6 to 6.9 meters per year on an azimuth of 35-130 degrees. Rose diagrams and historical wind records verify the sand dunes reach peak advancement rates during the warm season months of April to the middle of July. During this time of year the strongest winds prevail from west-southwest when the daily maximum wind speed is near 7 meters per second. Measurements of sand dune advancement rates from the years 1980-2012 show eolian activity has spatiotemporally fluctuated within the complex. </p><p> WDC sand was observed to have distinguishing textural attributes. Sediments from active dunes were mesokurtic, symmetrical, and trended towards moderately well sorted medium sand. Sediments from stable dunes were mesokurtic and trended towards moderately sorted fine sand but varied in skew from symmetrical to fine. Micro-stereoscopic inspection of bulk samples, thin sections, and the QFL ternary diagram revealed that sand traveling down the sediment transport corridor will physically weather from a White to Grey &amp; Very Pale Brown Litharenite into a Very Dark Grey to Light Yellowish Brown &amp; Pale Brown Feldspathic litharenite sand. The QAP ternary analysis and X-ray Diffractometry demonstrated that during the processes of dune stabilization and mineralogical maturation of sand the relative weight percent of total Quartz will increase (20 to 68%) and the percent relative abundance of lithic material will decrease (100 to 45%). Feldspar minerals were plentiful and ranged from 32 to 80 relative weight percent. The mineralogical maturity of sand when interpreted by the ratio of Quartz to Feldspar grades the maturation as low to fractionally intermediate. The QAP ternary diagram demonstrates there are distinct mineralogical differences within the sand and that mixing of sediments from various supply sources have contributed to its composition. Similar to findings from the Mojave Desert (Zimbelman &amp; Williams 2002) the abundance of Feldspar and lack of Quartz enrichment in WDC dune sand may imply the mineralogical maturity is directly inherited from the parent material. The lack of Quartz enrichment also indicates WDC is geologically young and most likely has not endured extended periods of inactivity. Prominent angular to subangular grains in WDC sediments suggest dune sand has not been transported over extremely long distances. Potential sediment supply sources for dune sand may include the Jungo terrane, Comforter Basin Formation, McDermitt-Santa Rose volcanic field, and sedimentary deposits from Lake Lahontan.</p>