<p> This thesis reconstructs the landscape evolution of the Billy Big Spring site (24GL304, Glacier County, north-central Montana) from the last glacial maximum to present through the analysis of sediment and soil samples collected from a transect of auger tests that bisected the site and surrounding landforms. Interpretations were drawn from stratigraphy, pedologic data, sedimentologic analysis and radiocarbon dating. The site landscape came into being in the late-Pleistocene, after Wisconsin-age glaciers retreated. Glacial retreat left a meltdown depression on the land that filled with water to form a pond, which persisted through the early-Holocene. The onset of the mid-Holocene (Altithermal) occurred before ~8,415 cal. yrs. BP, when increasingly arid conditions caused the water level to drop. The first radiocarbon dated human occupation of this site occurred during the Altithermal, ~7,030 cal. yrs. BP, after the eruption of Mount Mazama (~7,633 cal. yrs. BP). Arid conditions continued until ~7,000 cal. yrs. BP, when pond water re-expanded across the basin, marking the transition to the cooler late-Holocene. Sometime before 2,100 cal. yrs. BP, dry conditions returned, and the extent of the pond water decreased again. Since this time, overland alluvial processes have deposited sediments in the basin. Many hypotheses on how the Altithermal impacted the people of the Northwestern Plains have been proposed since the 1950s, but little agreement has been reached. This is due to the fact that there was great variation in how the Altithermal expressed itself throughout the Northwestern Plains. The human reactions to this phenomena cannot be explained simplistically for the region as a whole. This study shows that the Billy Big Spring site experienced drying during the Altithermal, but despite this, people continued to occupy this site. This evidence adds to the argument that the Altithermal climate of the Northwestern Plains did not have severe enough impacts to impose much hardship on its occupants.</p><p>

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Between 1977 and 2007, the Kaskawulsh Glacier underwent an overall decrease in volume of between 2.76 km3 water equivalent (we) and 4.60 km3 we, and a decrease in area of 2.27%. Volume losses are consistent with changes observed at most glaciers in the Yukon/Alaska region which are thinning and/or retreating (Arendt et al. 2006; Chen et al. 2006a; Larsen et al. 2007; Molnia 2007). The rate of volume change over the periods 1977-1995 and 1995-2007 remained constant at -0.52 km3 yr-1 we, while between 2000 and 2007 the glacier gained volume at a rate of 1.04 km3 yr-1 we. Gains in the recent 2000-2007 period result from prominent thickening in the accumulation area above 1989 m (+16.9 m) and minor thickening in the ablation area (+0.5 m). The observed thickening pattern is similar to patterns observed in Greenland (Chen et al. 2006b; Johannessen et al. 2005; Luthcke et al. 2008b), Antarctica (Davis et al. 2005), the Karakoram Himalaya (Hewitt 2005), New Zealand (Chinn 1999; Hooker and Fitzharris 1999), Scandinavia (Bamber et al. 2004; Chinn et al. 2005, Nesje et al. 2000), and Alaska (Arendt et al. 2008; Muskett et al. 2(03). Between 1956 and 2007, the glacier terminus retreated by an average of 655 m (13 m yr-1). No scaling ratio between terminus retreat and volume change could be established for the Kaskawulsh Glacier for the period 1977-2007.

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. / Arts, Faculty of / Geography, Department of / Graduate

The ability to accurately quantify shoreline variability along sandy beaches is essential in order to establish aggressive mitigation strategies, based on recent global climate change projections. This investigation employed a suite of coastal data -- topographic maps, aerial photography, high-resolution satellite imagery, and Lidar survey data-- to establish decadal trends of shoreline movement along sandy barrier islands on the northwest and southeast coasts of Florida. An extensive collection of data was assembled for the project, comprising nearly two dozen historic shoreline positions dating from the mid-19th century to the present. The techniques used to detect morphologic change with time were the Digital Shoreline Analysis System (DSAS) and a modernized analytical approach, Analyzing Moving Boundaries Using R (AMBUR). The latter approach was modified with a storm function to provide a forecast of the shoreline under predictions of more intense storminess. Results reveal that severe storms produce dramatic morphological alterations of the coast and in some cases, can result in shoreline retreat in excess of 50 meters during a single event. Special emphasis was placed on rates of change during the past decade and a half period (1995-2013) of active storm conditions. Of the three study areas analyzed, Little St. George Island returned the highest average rate of change of -4.33 m/yr in response to increased storminess. The average rate of change along Perdido Key in response to storms was -0.57 m/yr. Northern Merritt Island however, demonstrated the most stable shoreline of the three study sites and returned an overall mean rate of change of 0.41 m/yr. The results reveal that shoreline orientation, along with engineering projects, act over a variety of spatial and temporal scales to influence shoreline evolution. The trends of shoreline movement also indicate that nearshore bathymetry wields some influence on the behavior of local segments of a barrier island's shoreline. Tidal inlet dynamics were found to cause increased shoreline fluctuations and more notably, accelerated rates of erosion, especially immediately downdrift from the inlets. This project also enumerated volumetric and morphologic change in coastal dunes along a low-profile barrier island. The investigation established that natural dune recovery is directly related to the duration and frequency of storms. Further, the intensity of individual storms was found to be strongly correlated to trends in dune stability and shoreline evolution. Results show that the maintenance of viable dune fields is dependent on several ancillary factors. Such factors include: sediment supply via longshore drift or artificial nourishment, island width, dune field width, continuity of the dune complex, inner-shelf bathymetry and dune re-vegetation. In many cases, dune re-vegetation after storm passage delayed volumetric loss, favoring dune growth and reducing erosion. The analyses indicated that beach and dune recovery was initiated approximately six years following a major storm event. The results demonstrate that the most stable dunes were located along undeveloped and un-nourished segments of the island. In areas where nourishment had taken place however, foredune volumetric loss was significantly less pronounced. The results of this project provide a better and more detailed understanding of the vulnerability of coastal environments to the effects of climate change. / A Dissertation submitted to the Department of Earth, Ocean, and Atmospheric Science in partial fulfillment of the Degree Awarded:. / Spring Semester, 2015. / March 30, 2015. / barrier islands, sea-level rise, shoreline change, storms / Includes bibliographical references. / Stephen A. Kish, Professor Co-Directing Dissertation; Joseph F. Donoghue, Professor Co-Directing Dissertation; James B. Elsner, University Representative; William Parker, Committee Member; Yang Wang, Committee Member.

The recent geomorphologic history of the Apalachicola River can be related to local changes in sea level and the sediment output of the river. These changes can be observed in seismic data and boreholes collected in the bay. This project employed seismic, borehole and geochronologic data in order to map and better understand the paleogeography of the Apalachicola River and Bay region. These maps include; the seabed, the top of a mid-Holocene stratigraphic unit, the top of the Pleistocene, the top of the uppermost Mio-Pliocene unit, which includes a karst surface. In addition, Holocene-aged fluvial paleo-channels and paleo-deltas were identified in the subsurface and their paleogeographic relationships were mapped. The uppermost Mio-Pliocene aged sedimentary unit was described by Schnable (1966) on the basis of borehole data, as primarily sandy and clayey limestones, known as the Choctawhatchee Formation (Schnable, 1966). Huddlestun (1976) later described the same unit as the Intracoastal Formation, due to its location in the Intracoastal Waterway. Schmidt (1984) described the Intracoastal Formation as an easily recognizable stratigraphic unit composed of sandy, highly microfossliferous calcarenitic limestone. The thickness and dip of the Intracoastal Formation varies widely over the Apalachicola River region, due to the influence of the regions's largest subsurface structure, the Apalachicola Embayment (Schmidt, 1984). The embayment dates back to the early Tertiary and is the result of regional tectonic forces. The embayment is located between the Chatahoochee Anticline to the west and the Ocala Platform to the east (Rupert, 1997). The northern end of the Apalachicola Embayment narrows and extends into the Gulf Trough in southern Georgia (Rupert, 1997). It widens and deepens as it extends into the modern Gulf of Mexico (Rupert, 1997). The southernmost extent of the embayment is not well established due to the lack of offshore well data (Schmidt, 1984). The early to mid-Holocene paleo-deltaic features beneath the modern estuary migrated from west to east over the last approximately 7000 years. The specific subsurface features were identified and located by use of both seismic data and vibrocore logs. The depth of the features observed in the seismic data was calibrated based on bridge borehole transects collected from the Eastpoint to Apalachicola and the Apalachicola to St George Island bridge-causeways. The Apalachicola River's paleo-discharge was determined by using the Manning equation to calculate the maximum discharge of the river, based on the channel geometry and regional gradient. Several paleochannel profiles were found and measured. The calculated paleo-discharge was 86,000 cfs. This discharge was based on the entire cross-section of the river and therefore represents a bank-full or maximum discharge. The modern and paleo-streamflow were found to be comparable. The calculated paleo-discharge value falls within the range of the average annual peak discharge of the modern Apalachicola over the last 30 years. A possible explanation comes from Holocene climate data extracted from the palynology of long cores from regional lakes. Data from two lakes indicates that climate in the region has changed little in the past 6,000 years and perhaps for as much as 8,000 years. The paleofluvial history of the region's largest river, the Apalachicola, appears to corroborate that finding. / A Thesis Submitted to the Department of Geological Sciences in Partial Fulfillment of the Requirements for the Degree of Master of Science. / Fall semester, 2008. / November 24, 2008. / Geomorphology, Apalachicola Bay, Florida, Seismic, Discharge, Delta, Karst / Includes bibliographical references. / Joseph F. Donoghue, Professor Directing Thesis; Lynn Dudley, Committee Member; Bill Hu, Committee Member.

The present study was focused on developing a shoreline change forecast and wetland response model for Dorchester County, MD, to evaluate the vulnerability of wetlands to shoreline erosion and inundation due to relative sea level rise. The model considers the following forces involved in wetland stability and sustainability: inundation (as a function of topography and sea-level rise), shoreline erosion, vertical accretion and horizontal migration. To predict the long-term risk to nearshore wetlands and the potential habitat zone for wetlands in the next 50 years, shoreline change due to inundation and erosion/accretion was assessed within the frameworks of two-dimensional and three-dimensional analyses. To that end, three different scenarios were taken into account in the shoreline change forecast. The first (conservative) scenario estimated the future shoreline positions based on historic sea-level rates of change and historic erosion/accretion rates. The other two scenarios employed accelerated rates of sea-level rise and accelerated rates of shoreline erosion/accretion in the shoreline forecast. Two different approaches were employed to spatially analyze and combine the outputs of the projections based on inundation and erosion. A Maximum Change approach and a Characterization of the Inundation Forecast were carried out in each scenario. The future location of the shoreline was defined as the wetland-water boundary. The wetland-upland boundary was defined based on current topography (elevations at 2 times the tidal range above mean low water), and the potential wetland habitat was restricted to areas that are not presently developed and/or not behind a shoreline defense structure. The outputs of this model allow identification of potential future wetland habitats where wetland protection and restoration strategies can be directed. This model approach can serve as a prototype for expanded investigations in other coastal habitats.

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