<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> Fluvial suspended sediment is a master variable affecting a wide range of fluvial and coastal environmental processes, and dominating the terrestrial mass flux to the oceans. Although it has long been recognized that relationships between suspended sediment concentration and discharge are not stationary in small, mountainous rivers over time scales from hours to decades, most studies continue to assume stationarity. This collection of studies directly addresses the issue of non-stationarity in the suspended sediment &ndash;discharge relationship of the Salinas River, central California, and examines the progression of abandoned channel fill sequences in the Eel River Estuary of northern California. </p><p> Preceding these studies is a methodological analysis of the pretreatment of fluvial and marsh sediments for particle size analysis. Pretreatment of sediment with hydrogen peroxide to remove organic constituents and aid deflocculation is a common component of particle size analyses of terrestrial and marine sediments. The first chapter presents the quantitatively determined effect of a range of treatment levels on particle size distribution among four sediment types representing a range of mineral/organic particle size distributions, organic content and particle characterization (charcoal or detrital plant material). </p><p> The following three chapters examine the effects of antecedent basin conditions on the suspended sediment &ndash; discharge relationship in the Salinas River. In chapter two, forty-five years of suspended sediment data from the lower Salinas and 80 years of hydrologic data were used to construct hydrologic descriptors of basin preconditioning and test the effects of these preconditions on suspended sediment behavior. Fine (diameter (<i>D</i>) &lt; 63 &mu;m) and sand sized (<i>D</i> > 63 &mu;m) sediment were found to respond differently to antecedent hydrologic conditions. Fine sediment was most sensitive to flushing flows of moderate discharge (10 &ndash; 20x mean discharge (<i>Q_mean</i>) that led to lower subsequent fine sediment concentrations, while sand concentrations were generally decreased by periods of drought and longer elapsed time since a wide range of discharges acting as maintenance flows. </p><p> Chapter three examines the interannual to decadal scale persistence of suspended sediment &ndash; discharge relationship states in the lower Salinas River, assesses the role of antecedent hydrologic conditions in controlling these patterns, and addresses their relationship to El Ni&ntilde;o Southern Oscillation (ENSO) climatic states. The decadal scale variability in suspended sediment behavior was influenced by interannual to decadal scale fluctuations in hydrologic characteristics, including: elapsed time since small (&sim; 0.1x Qmean), and moderate (&sim; 10x Qmean) threshold discharge values, the number of preceding days that low/no flow occurred, and annual water yield. El Ni&ntilde;o climatic activity was found to have little effect on decadal-scale fluctuations in the fine suspended sediment &ndash; discharge relationship due to low or no effect on the frequency of moderate to low discharge magnitudes, annual precipitation, and water yield. However, sand concentrations generally increased in El Ni&ntilde;o years due to the increased frequency of moderate to high magnitude discharge events, which generally increase sand supply. </p><p> Chapter four brings to bear the decadal scale persistence of suspended sediment - discharge behavior, the effects of antecedent hydrologic conditions, and ENSO influences on the estimation of inter-decadal scale sediment flux from the Salinas River. The longer sampling records employed in this study and incorporation of decadal scale behavior or antecedent hydrologic conditions resulted in average annual load estimates of 2.1 or 2.4 Mt, in comparison to earlier estimates of &sim; 3.3 Mt by previous researchers. El Ni&ntilde;o years dominated the sediment budget by producing on average ten times more sediment than non-El Ni&ntilde;o years. </p><p> Chapter five proposes a modification of the current generic model for abandoned channel fill stratigraphy produced in unidirectional flow river reaches to incorporate seasonal tidal deposition. This work was based on evidence from two consecutive abandoned channel fill sequences in Ropers Slough of the lower Eel River Estuary. Planform geomorphic characteristics derived from these images were used in conjunction with sub-cm resolution stratigraphic analyses to describe the depositional environment processes and their resultant sedimentary deposits. The abandoned channel fill sequences appeared to differ due to the topographic steering of bed sediment transport and deposition previously identified in rivers experiencing only unidirectional flow, while also expressing the seasonal dichotomy of fluvial and tidal deposits.</p>

<p> New stratigraphic and geomorphic data from the Santa Maria Basin, California, suggests that the major basin-bounding Little Pine fault system has been acting in a primarily reverse offset fashion since the late Pleistocene. A series of stratigraphic columns in the Plio-Pleistocene Paso Robles Formation measured along the Little Pine fault indicate that there was episodic uplift during the latest Pleistocene. A 20-40% increase in the percent composition of resistive, Franciscan Complex-derived cherts within active drainages indicate that uplift of the San Rafael Mountain front increased rapidly since the deposition of older sediments. The shape of stream profiles created along the Little Pine fault suggest ongoing uplift associated with the central and southeastern segments of the fault, with a lesser amount of uplift occurring further northwest along the Little Pine fault. A number of ridgeline profiles were also created which exhibit significant jumps in topography near, or just northeast of the Little Pine fault, suggesting that recent uplift is responsible. The ridgeline profiles also suggest an increased rate of uplift adjacent to the central and southeastern segments of the Little Pine fault zone, in agreement with the along-strike variations in uplift suggested by the stream profiles. Stream traces were also examined for deflections as they flowed across the Little Pine fault, but most show no significant lateral offset.</p>