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Articles 1 - 19 of 19
Full-Text Articles in Physical Sciences and Mathematics
Investigation Of Pervasive Clay Layers And Their Effect On Groundwater Flow Using Electrical Resistivity Tomography In The San Antonio Groundwater Basin, James M. Carlson
Investigation Of Pervasive Clay Layers And Their Effect On Groundwater Flow Using Electrical Resistivity Tomography In The San Antonio Groundwater Basin, James M. Carlson
Natural Resources Management and Environmental Sciences
The United States Geological Survey is developing an integrated hydrologic model of the San Antonio Creek Groundwater Basin to better understand and simulate the integrated surface water and groundwater system. An abrupt 60 meter offset in groundwater depth over a distance of less than one kilometer is observed in well readings within the Cañada De Las Flores region of the groundwater basin. Abrupt changes in groundwater levels are often explained by the presence of a fault in the subsurface vertically offsetting sedimentary units. However, observations of the structural geology of this region indicates that faulting is unlikely and suggests an …
Investigation Into Strath Terrace Production In The Mud Hills, California, Patrick Morley Miller
Investigation Into Strath Terrace Production In The Mud Hills, California, Patrick Morley Miller
Natural Resources Management and Environmental Sciences
Rainbow Basin and Owl Canyon comprise deeply dissected uplands in the Mud Hills region near Barstow, California in the western portion of the Basin and Range geologic province. These erosional landscapes are formed in sediment deposited in a Miocene-time extensional basin. The basin was then filled with sediment before being inverted due to tectonic uplift beginning roughly 10 Ma. Sometime after 250 to 300 ka strath terraces were produced and preserved in the two drainage basins in Rainbow Basin, but not in the single drainage basin of Owl Canyon. The reason behind this difference is the main problem to be …
Tectonic Controls On Alluvial Fan Dissection In The El Paso Mountains, Michael Thomas Gaffney
Tectonic Controls On Alluvial Fan Dissection In The El Paso Mountains, Michael Thomas Gaffney
Natural Resources Management and Environmental Sciences
The localized dissection of alluvial fans along the western El Paso Mountains is under question. A relatively minor, south dipping normal fault, previously unmentioned in scientific literature, cuts across Quaternary terraces and alluvial fans in the piedmont of the El Paso Mountains. The linear trend of footwall uplift and the pattern of stream incision into the footwall adjacent to the linear trend of footwall uplift reveal that fan dissection is a result of base level fall caused by ongoing tectonism along the El Paso fault system. The regional importance is discussed as the timing of faulting reveals relatively recent uplift …
A Study Of Marine Terrace Formation Along The California Central Coast, Mary C. Devlin
A Study Of Marine Terrace Formation Along The California Central Coast, Mary C. Devlin
Natural Resources Management and Environmental Sciences
Marine terrace formation is in many instances attributed to wave action, and shore platforms are often called “wave-cut”. However, alternative models for marine terrace formation suggest that other types of physical and chemical weathering have a more central role in the formation of marine terraces than is widely acknowledged. Roering and Retallack (2012) concluded that the roles of subaerial physical and chemical weathering are significant, and played a major role in the formation of the terraces. In this study, weathering of beach cliffs and shore platforms associated with marine terraces at eight sites in two different locations along the central …
Stream Terrace Genesis Along Bunte Creek In The Elkhorn Plain, Ca, Madi Allgaier, Shelley Anderson, Duncan Lord
Stream Terrace Genesis Along Bunte Creek In The Elkhorn Plain, Ca, Madi Allgaier, Shelley Anderson, Duncan Lord
Natural Resources Management and Environmental Sciences
There are several factors influencing terrace genesis and terrace types in Bunte Creek. Strath terraces exist at upper Bunte Creek, whereas thick fill terraces exist at lower Bunte Creek. Analysis of these terraces leads to insight on what specific factors lead to their formation. Terraces were mapped along the extent of Bunte Creek. Sediment data and terrace-height data were collected for in order to make a complete analysis of the terraces. Tectonic uplift led to incision and strath terrace genesis at upper Bunte Creek. Climatic forcing and base-level rise caused alluvial aggradation behind a shutter ridge that intersects lower Bunte …
Structure And Geochronology Of The White Fork Pluton, Southern Sierra Nevada, Ian Richard Mahaffey
Structure And Geochronology Of The White Fork Pluton, Southern Sierra Nevada, Ian Richard Mahaffey
Natural Resources Management and Environmental Sciences
The Sierra Nevada batholith represents an archetypal continental arc, although the style of deformation throughout the history of the arc is only poorly understood, in part due to the voluminous nature of Late Cretaceous magmatism that has overprinted earlier structures. The purpose of this study is to gain a better understanding of pre-Late Cretaceous deformation in the Sierra Nevada batholith through a structural and geochronological study of the Jurassic White Fork pluton. A Jurassic age for the White Fork pluton is indicated by its inclusion of numerous 148 Ma Independence dikes, and geochronology on the White Fork pluton is limited …
Detrital Zircon Geochemistry Of The Nacimiento Block, Santa Ynez Mountains, California, Vincent Zhao
Detrital Zircon Geochemistry Of The Nacimiento Block, Santa Ynez Mountains, California, Vincent Zhao
Natural Resources Management and Environmental Sciences
The long-lived California section of the North American Cordillera is one of the most studied continental margins in the world; however, erosion and deformation in areas along the San Andreas Fault and the Sur-Nacimiento Fault has erased sections of the Cordillera which could provide insight in Cordilleran processes. The lost sections are partially preserved in detrital zircons deposited alongside the arc in fore-arc basins such as in the Toro Formation of the Nacimiento block which represents the coastal central California equivalent to the Great Valley Group, located in the Santa Ynez Mountains. Geochemical analysis of the detrital zircons from the …
Investigating Meter Scale Topographic Variation As A Factor Of Monterey Pine (Pinus Radiata) Growing Conditions At Kenneth Norris Rancho Marino Reserve, Cambria, Ca, William J. Meyst
Natural Resources Management and Environmental Sciences
Endemic Monterey pine (Pinus radiata) is limited to three locations in California due to its unique ecological requirements. This project was conducted to investigate spatial growth patterns ofMonterey pine over complex ground surfaces. The coastal hills of Rancho Marino Reserve, Cambria, were surveyed using four 150-m transects to quantify and record ground surface features and growing conditions ofMonterey pine. Changes in elevation of each transect were measured using an Abney level. Linear ground surfaces were found at 86% (344 of 400) of survey nodes. Convex ground surfaces were found at 10.5% of survey nodes (42 of 400). Of …
Relationship Of Joint Sets To Folded Diatomite Bedding Of The Miguelito Member Of The Pismo Formation In Montaña De Oro State Park, Michael Mcmahan
Relationship Of Joint Sets To Folded Diatomite Bedding Of The Miguelito Member Of The Pismo Formation In Montaña De Oro State Park, Michael Mcmahan
Natural Resources Management and Environmental Sciences
This study was conducted to determine if the orientations of observed joint sets in the late Miocene diatomite bedding of the exposed Miguelito Member in Montaña de Oro State Park relate to the San Andreas wrench fault compressional forces that caused folding of the formation. Strikes and dips of bedding planes and their corresponding first and second generation joint sets were gathered and compiled into a stereonet program for analysis. A cross section of the bedding plane data shows compressional antiform (fold axis oriented ~304/013) and synform (fold axis oriented ~300/001) features. Previous studies indicate post Miocene, tectonic shortening with …
Geoelectrical Detection Of Water Table Depth At Two Locations In The Los Osos Groundwater Basin, Hallie A. Douglas
Geoelectrical Detection Of Water Table Depth At Two Locations In The Los Osos Groundwater Basin, Hallie A. Douglas
Natural Resources Management and Environmental Sciences
The city of Los Osos sits on top of a coastal groundwater aquifer which is the sole supplier of all its residential, agricultural, and industrial water needs. Lacking a sewer system, the upper aquifer became progressively contaminated with nitrates over several decades. Groundwater pumping eventually shifted to the lower aquifer, however seawater intrusion of the lower aquifer caused by over-pumping has further degraded water quality. The Los Osos groundwater basin provides an excellent field region to examine the utility of geophysical methods for characterizing aquifer structure. In this study shallow (<20 >m) electrical resistivity imaging methods were performed at two …
Surficial Geologic Map Of Kings Canyon: Implications For Relatively Slow Stream Incision Rates, Andrew Farris
Surficial Geologic Map Of Kings Canyon: Implications For Relatively Slow Stream Incision Rates, Andrew Farris
Natural Resources Management and Environmental Sciences
Most of the Kings River in the Sierra Nevada Mountains of California has responded to regional uplift with rapid incision, creating the deepest canyon in the United States. However, Kings Canyon near Cedar Grove is still a mountainous relict landscape with little evidence of fluvial incision. Mapping took place in the Cedar Grove area of Kings Canyon to assess factors and/or processes causing relatively low stream incision rates in the region during Holocene time. A surficial geologic map was created in the field, along with visual observations of the South Fork of the Kings River and characterization of geologic map …
Lower San Luis Obispo Creek Stewardship Plan, Raven Lukehart, Daniel Bohlman
Lower San Luis Obispo Creek Stewardship Plan, Raven Lukehart, Daniel Bohlman
Natural Resources Management and Environmental Sciences
No abstract provided.
Late-Quaternary Channel Migration In Red Rock Canyon State Park, California; Implications For Regional Tectonics, Kirk Forrest Townsend
Late-Quaternary Channel Migration In Red Rock Canyon State Park, California; Implications For Regional Tectonics, Kirk Forrest Townsend
Natural Resources Management and Environmental Sciences
The Iron Canyon Valley, located at the southern end of the eastern Sierra Nevada at the boundary between the Mojave and Basin and Range tectonic provinces, exhibits clear evidence, over graded timescales, of development through monoclinal shifting, which is the tendency of streams flowing parallel to strike over sedimentary rocks to shift down-dip. Although the character of the valley and bedrock dip indicates development through monoclinal shifting, the current stream network is located up-dip on the east side of the valley. Mapping the surficial geology of the valley revealed the presence of dissected alluvial surfaces approximately 85 meters above modern …
Geochemistry And Geochronology Of The Central Metasedimentary Belt Boundary Thrust Zone Thrust Sheets In Southern Ontario, Grenville Province, Kenjo Agustsson
Geochemistry And Geochronology Of The Central Metasedimentary Belt Boundary Thrust Zone Thrust Sheets In Southern Ontario, Grenville Province, Kenjo Agustsson
Natural Resources Management and Environmental Sciences
Studies of pre-Grenvillian (1.4–1.3 Ga) plutons offer insight into the dynamics of arc amalgamation and backarc rifting prior to continental collision in the Ottawan orogeny. The Central Metasedimentary Belt boundary thrust zone (CMBbtz) is a northeast–southwest trending thrust zone consisting of metaplutonic thrust sheets enveloped in gneissic tectonites and calcitic– dolomitic marbles. Tonalitic CMBbtz thrust sheets (Dysart and Redstone) are made up of upper amphibolite-facies, foliation-concordant metatonalites (+ amphibole ± biotite ± accessory zircon and titanite) and amphibolites (± biotite ± clinopyroxene), and are located in the southern Ontario Grenville Province. These thrust sheets are thought to have formed and …
Determining Ancient Movement Of The Sur–Nacimiento Fault Zone Using Detrital Zircon Geochronology, Jennifer Per Lee
Determining Ancient Movement Of The Sur–Nacimiento Fault Zone Using Detrital Zircon Geochronology, Jennifer Per Lee
Natural Resources Management and Environmental Sciences
Middle Cretaceous movement along the Sur–Nacimiento Fault has implications for our understanding of how convergent tectonic margins evolve and for the architecture of forearc basins. Traditional explanations suggest an autochthonous California Mesozoic Forearc that underwent sinistral or thrust displacement; although recent research suggests either an allochthonous forearc or an isolated Nacimiento Block that experienced significant dextral displacement. Detrital zircons obtained from the Great Valley Group within the Nacimiento block provide age distribution patterns that can help identify sources of sediment deposition and therefore the past location of the Nacimiento block. Using U-Pb detrital zircon geochronology, we have discovered a dominance …
Factors Influencing Landslides In The Bittercreek Wildlife Refuge, David Mceachern
Factors Influencing Landslides In The Bittercreek Wildlife Refuge, David Mceachern
Natural Resources Management and Environmental Sciences
No abstract provided.
Soil Mapping On A Swanton Pacific Ranch Rangeland, Thomas N. Witman
Soil Mapping On A Swanton Pacific Ranch Rangeland, Thomas N. Witman
Natural Resources Management and Environmental Sciences
Knowledge of soils has become very important in most land based enterprises. The understanding of soils is necessary for all different types of land management projects. The USDA mapped all of the soils in the United States starting in the late 1950’s to provide the necessary information. However because the mappers often times had to map entire counties in short amounts of time ,did not have modern technology, and had rather a vague operating procedure, there was no way to be accurate on the small scaled. To solve this problem I evaluated Dr. Ron Taskey’s landscape hierarchy, a method that …
Post-Fire Near-Surface Runoff From Small-Scale Rainfall Simulations, Santa Cruz Mountains, Michael Founds
Post-Fire Near-Surface Runoff From Small-Scale Rainfall Simulations, Santa Cruz Mountains, Michael Founds
Natural Resources Management and Environmental Sciences
The influence of environmental variables on the runoff response to a fire is poorly understood. Small-scale rainfall simulation was used to study the factors impacting near-surface runoff following the Lockheed Fire, which occurred on August 12, 2009. A variable speed rainfall simulator was used to rain on 15 different test plots at an average rate of 50mmh-1. Variables of burn severity, time following the fire, soil parent material, vegetation type, and presence of a duff layer were all analyzed using the ratio of runoff to rainfall. The difference in-between burned sites and similar control sites were 19±6%. Only …
Aerial Reconnaissance Of Stream Terraces And Landslides Within Bitterwater Creek Watershed In Kern County, California, Zachary Smith
Aerial Reconnaissance Of Stream Terraces And Landslides Within Bitterwater Creek Watershed In Kern County, California, Zachary Smith
Natural Resources Management and Environmental Sciences
No abstract provided.