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Collection Description

The Department of Geological Sciences has a long-standing Senior Thesis research option for the B.S. Degree which involves a written thesis, and a public oral presentation done under the supervision of a faculty member. These independent research projects typically involve field work and laboratory analyses of samples, but can also include laboratory-based experimental projects, numerical modeling of geologic phenomena and literature reviews. Senior theses are kept in the permanent collection of the Malcolm A. Love Library on the SDSU campus.

Authors hold full copyright ownership of their original works. Please contact the repository manager at digital@sdsu.edu for any further questions.

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Teaching and learning geology in the outdoor field environment: A case study with in-service teachers
Research and undergraduate training in the earth sciences are strongly field-based, but the field environment is rarely used for non-majors or for teacher education. Research into the design and effectiveness of earth science field trips suggest that field experience enhances the learning of fundamental geological concepts, but only if field trip design minimizes unfamiliarity with surroundings and is process and investigation oriented. This project tests protocols and techniques for using the outdoor field environment to increase elementary school teachers' content knowledge and confidence in field-based, inquiry-based teaching. Specifically, the research is aimed at quantifying the impact of carefully designed field learning on teachers' understanding of sedimentary systems and environmental change through time as recorded in sedimentary rocks. Measurements were made of prior knowledge, understanding gained after a preparatory classroom session, and final resulting content knowledge after a subsequent one-day directed inquiry field experience at Torrey Pines State Reserve. Changes in attitudes toward science and Earth science were also tracked through this process. We have also conducted a short case study investigation involving four individual teachers from the San Diego City Schools who participated in this program to assess resulting changes in their classroom teaching approach. The data suggests that content knowledge of sedimentary structures, depositional environments, and geologic time were enhanced in the field. The data also indicates that the teachers' confidence to use the field environment to teach inquiry-based science was increased following the field experience. This study suggests that in-service teachers, as well as pre-service teachers and other non-geology majors are likely to benefit in terms of increased content knowledge and conceptual understanding from the incorporation of directed-inquiry field experiences in geoscience courses., San Diego State University
Tephrachronology, tephrastratigraphy, and regional implications of tephra deposits, El Rosario area, Baja, California, Mexico
The El Rosario area is located 30° north by 115° 45' west along the Pacific coast of Baja California, Mexico. The geology of the area consist of Late Cretaceous marine and non-marine mudstones, silstones, sandstones, and conglomerates. Tephra deposits dated at approximately 77 m.y. and consisting of both air-fall and ash-flow tuffs are discontinuously exposed throughout a maximum area of 225 sq. km., but pre-dominantly concentrated within an 80 sq. km. sector adjacent to the coastline. These tephra deposits are contained within the El Gallo Formation, the lithology of which indicates a near shore lagoon and playa environment. The mechanics of the depositional basin have played a significant role in the preservation and subsequent lithology of the tephra units; most air-fall deposits being altered to sandy and silty quartz­rich biotite tuff. The remaining exposures consist of vitric matrix ash-flow tuffs and relatively pure vitric air-fall tuff that is altered to olive green conchoidal bentonite. Two episodes of tephra deposition are recognized. The oldest is a relatively pure air-fall tuff that is bext exposed on Cerro Rayado, and a younger unit which is recognized by a thin brown ash-flow tuff which underlies white air-fall beds and is best exposed in a complete section at location 9. The tephra deposits are thickest and apparently more prevalent in the southwest portion of the area, suggesting a southern or western source. No volcanic centers are known to have existed in late creataceous time proximal to the El Rosario area. Three possible sources are inferred., San Diego State University
The 2011 Tohoku-Oki earthquake: Cross correlation of bathymetric data model a horizontal displacement reaching the Japan Trench Axis
We studied the bathymetric data acquired before and after the 11 March 2011 Tohoku-­Oki Earthquake [moment magnitude (MW) 9.0] by Fujiware et al. In 1999 and 2004, multibeam bathymetric data were acquired during active source seismic surveys along the same track across the Japan Trench Axis using a SeaBeam 2112 swath mapping sonar with a 12 kHz frequency and a 2° x 2° beam width. We estimated the horizontal and vertical displacement by cross correlating data from the 1999, 2004 and 2011 survey, revealing that the displacement extended out to the axis of the Japan Trench,suggesting that the fault rupture reached the trench axis and caused the sea floor on the outermost landward region to moved approximately 50 meters horizontally east-­southeast and about 10 meters upward. Our data also revealed the large horizontal displacement lifted the sea floor up to 16 meters on the landward slope in addition to the vertical displacement. This uplift was an important factor in he generation of tsunami waves. The effect of horizontal displacement is usually neglected, however, when the tsunami source is on a steep slope and the horizontal displacement is large relative to the vertical displacement, as in the Tohoku-­Oki Earthquake, the effect becomes significant and the horizontal displacement becomes an important source to the tsunami wave generation., San Diego State University
The Alberhill claybeds in the Silverado Formation of Southern California, Paleosol weathering or K-Pg impact deposit?
Paleogene strata in southern California contain clay horizons at numerous localities that have been interpreted by most workers as ancient paleosols that formed in response to weathering under sustained humid tropical conditions. The Claymont Clay Bed in the Silverado Formation at the Alberhill clay pit in the northern Santa Ana Mountains is an example, which however has been recently reinterpreted to be the result of weathering from acidic solutions generated by the Chicxulub K-Pg impact event (Busch & Miller, 2016). The potential impact layer in the Silverado Formation at Alberhill is a 2-3 cm thick clay layer within heavily oxidized sandstone/siltstone. Samples were collected and analyzed by X-ray diffraction (XRD) and X-ray fluorescence (XRF) to determine the chemical and mineral compositions across and below the assumed boundary layer. XRD analysis shows that the Alberhill clay is dominated by kaolinite with minor illite, similar to K-Pg boundary claystone from the Raton basin in Colorado and New Mexico (Izett, 1987). XRF trace element analysis of the Alberhill clay show that concentrations of Ni, Co and Zn are similar to values for average shale, while impact layer claystone from the Raton basin have dramatically lower contents of these elements. K-Pg boundary marine claystone samples from Denmark in contrast have far higher concentrations, perhaps from dissolving and concentrating the metals in the sea floor or possibly from another meteor impact at the end of the Cretaceous. Although the Ni, Co and Zn contents of the Alberhill clay layer are not supportive, the possibility of K-Pg impact hypothesis cannot be conclusively ruled out based on data presented here., San Diego State University
The Little Picacho Wash formation and the timing of exposure for the Winterhaven formation, Picacho State Recreation Area, Southern California
At Picacho State Recreation Area a variable thick sequence of carbonate, sandstone, and gravel underlies the Oligocene Quechan volcanics and overlies the Jurassic Winterhaven Formation. This dominantly elastic sequence is prominently exposed in gullies lying just to the east of Little Picacho Wash, and is herein informally referred to as the Little Picacho Wash formation. The lowest part of the Little Picacho Wash formation consists of about 3 meters of carbonate and interstratifled calcareous sandstone. Carbonate beds are mostly peloidal limestone and grade from pure limestone through sandy limestone to calcareous sandstone. Overlying this lower portion is a section of mostly paraconglomerate that reaches a maximum thickness of~ 150 meters. Subround to subangular gravel in the paraconglotnerate varies from pebble to boulder in size. Thin section study indicates that clasts vary from chlorite-grade greenschist facies metasandstones to metavolcanic derived from flows and pyroclastic material. Metavolcanic clasts on the conventional trace-element magma-series discrimination diagram range from basalt to andesite and rhyolite/dacite. On the trace element magma-series discrimination diagram, the compositional variants analyzed form the Little Picacho Wash formation cluster within fields defined by the chemistry of metavolcanic rocks analyzed from the Winterhaven Formation. Hence, I conclude that the Winterhaven Formation must have been exposed at the Earth's surface during deposition of the Little Picacho Wash formation. Such a conclusion leaves open the possibility that the initial stages of growth of the Chocolate Mountains anticlinorium may have occurred during deposition of the Little Picacho Wash formation., San Diego State University
The Manix Fault between Manix and Afton Canyon, San Bernardino County, California
The Manix Fault is an east-northeast trending zone of anastomosing fractures located 21 to 35 miles east of Barstow in the east-central Mojave Desert of California. The Manix Fault cuts Mesozoic(?) crystalline basement rocks, Miocene and post-Miocene volcanic rocks, post-volcanic fanglomerates, and late Pleistocene Manix Lake beds. Move­ment along the fault may have begun as early as late Tertiary, as evidenced by possible intermittent faulting in a post -Miocene fanglomerate unit, but definitely has been active in the Quaternary, as evidenced by faulted late Pleistocene lake beds and recent earthquakes (April 10, 1947). Sense and magnitude of slip along the fault are uncertain; however, left-lateral separation of as much as three miles may be indicated by a faulted post-Miocene granitic-clast fanglomerate in the northern Cady Mountains., San Diego State University
The Pleistocene Bautista Formation and the San Jacinto Fault: Setting the stage for future studies
The variably thick, Pleistocene Bautista formation is scattered throughout the San Jacinto fault zone. Based on published data, the Bautista beds were derived from eastern sources, after termination of Pliocene movement on the Western Salton Detachment, and during the Pleistocene development of the San Jacinto fault zone. A principal goal of fault zone architectural studies is to understand fully what happens to rocks as they become incorporated into the damage zone lying adjacent to fault cores. Unfortunately, the petrology of sandstones within the Bautista formation has never been studied. To mitigate against this deficiency in data, I undertook a detailed study of sandstones in the Bautista formation at the Hog Lake locality. At the Hog Lake locality, a SW verging thrust fault appears to merge off the main trace of the San Jacinto fault. It places, high grade metamorphic rocks of the pre-mid Cretaceous Burnt Valley complex of the hanging wall block, over pebbly to cobbly sandstones of the Bautista formation in the footwall. Sixteen samples of sandstone were collected across the exposed outcrop belt of the Bautista and were thin sectioned and point counted. Each thin section was chemically stained to distinguish between plagioclase and K-feldspar. The Gazzi-Dickinson point-count method was used, and 300 points at a spacing of 1 mm were identified and tabulated. The results of this exercise indicate that sandstones at the Hog Lake locality are poorly to very poorly sorted and are composed of a framework population that is dominated by very angular to subround crystal and rock fragments. On the classification scheme of W.R. Dickinson, all samples plot in the feldspathic sandstone field. Not surprisingly, on the QFL provenance-discrimination diagram developed by W.R. Dickinson and students in 1983, samples spread about the boundary separating the basement uplift from transitional continental block fields. In thin section, plutonic micro-phaneritic rock fragments are significantly more abundant than are metamorphic aphanitic rock fragments. The latter commonly contain sillimanite ± K-feldspar. Plagioclase to total feldspar ratios when compared to standard ranges for different plutonic rock types indicate a predominantly granodioritic source. Tonalitic and high-grade metamorphic rocks contributed lesser amounts of sandsized detritus. Porosity was determined from grain and bulk density measurements. Outside the zone of damaged rock adjacent to the overthrust Burnt Valley Complex, porosity varies from ~15%-30%., San Diego State University
The Pleistocene Bautista Formation: Clay mineralogy and geochemistry
Near Hog Lake NE of Anza, California, the Pleistocene Bautista formation contains a vertebrate fauna consisting of horse, tapir, camel, antelope, ground sloth, and rabbit (Frick, 1921). This faunal assemblage is generally indicative of a Pleistocene climate that was cooler and moister than that existing today. Based on published paleocurrent and petrological studies, material making up the Bautista was derived mainly from eastern plutonic and metamorphic sources. These and other data indicate that the Bautista formation were deposited after Pliocene movement on the Western Salton Detachment had ceased, and as the San Jacinto fault zone developed. The clay mineralogy making up the < 2 μm sized fractions of sandstones in the Bautista formation is dominated by smectite, kaolinite, and illite, with a lesser component of mixed-layer illite/smectite. Given the feldspathic composition, poorly sorted, and generally angular nature of sand sized detritus in Bautista sandstones, it is likely that debris flows sampled during this study did not travel far. Hence, the clay mineralogy may reflect the overall Pleistocene weathering pattern within a moderately wet climate as sediment traversed the source to sink depositional system. Molar A, CN, and K data derived from chemical analysis of Bautista sandstones spread from the composition of unweathered granodiorite toward the field of unweathered high-grade metamorphic rocks analyzed from the Burnt Valley complex. Principal component 1 describes 99% of the variance in the Bautista sandstone data about the compositional linear trend. These results suggest that sandstones of the Bautista Formation were derived largely from granodiorite and variable, but generally lesser, amounts of high-grade metamorphic rock., San Diego State University
The Potter scale of climbability
Climbability is here defined as the ability of a cliff face to be ascended from the ground up using traditional, non-invasive climbing techniques. A study was undertaken in order to assess the climbability of several sedimentary rock units and to develop a scale that quantifies climbability. A link was found between climbability and a unit's sedimentary characteristics. Twenty cliff sections in California, Arizona, Nevada, and Utah were analyzed and given a climbability (CB) score of 1-38 based on fracture length, fracture size, friction, friability, and cleanness. The Total CB score for each cliff was plotted against percentages of framework, matrix, cement, porosity, quartz, feldspar, lithologic fragments, sorting, roundness, and grain size. The most important factors in achieving a high CB score are high quartz content, a low percentage of rock fragments, and a high degree of sorting, with Pearson correlations of .849, -.822, and .802, respectively. Correlations between individual sedimentary characteristics and CB factors show a strong relationship linking these characteristics with favorable fracture size and length. Eolian dunes ean the highest CB scores, and the lowest scores are given to sedimentary rocks originally deposited in lacustrine/lagoonal or in alluvial fan environments., San Diego State University
The Sacatone Springs tonalite: Of eastern or western origin?
The Sacatone Springs gneissic tonalite is located within the Tule Mountain roof pendant in the eastern zone of the Peninsular Ranges batholith (PRB), and outcrops near the middle of the 94 Ma La Posta pluton. It has some features similar to those of western-zone rocks, and others similar to those of eastern-zone rocks. The purpose of this study is to determine whether it is an eastern- or western-type rock of the PRB. Well-developed foliation, abundant mafic inclusions, and subhedral to anhedral mafic minerals are found in both western-zone plutons and the Sacatone Springs tonalite. However, the Sacatone Springs tonalite has primary sphene and no magnetite, which are characteristics of eastern-zone plutons. Simply by analyzing the mineralogical and textural features, a realistic conclusion cannot be drawn. Geochemical data suggest that the Sacatone Springs tonalite is an eastern-type rock. Relatively high Sr content, negligible Eu anomalies, and relative depletion in the heavy rare-earth elements are characteristics of eastern-zone rocks and the Sacatone Springs tonalite. The tonalite samples fit nicely into the linear trend displayed by La Posta rocks on trace element variation diagrams. They also fit into the La Posta range on rare-earth element plots. The Sacatone Springs tonalite appears to be an eastern-type rock, and it is likely a remnant border facies of the La Posta pluton., San Diego State University
The West Bullion-Mesquite Lake Fault step-over: Assessment and comparison with faults of the Eastern California Shear Zone, Twenty-Nine Palms Marine Corps Base, California
The purpose of this investigation was to determine where active fault strands exist within the West Bullion Fault-Mesquite Lake fault step-over, and to ascertain whether or not these would pose a threat to new building additions at the Twenty-Nine Palms Marine Corps Base, in California. During the summer of 2011, the Naval Facilities Engineering Command (NAVFAC) proposed three new buildings to be added to the base. This would include a Quality of Life Center consisting of a bachelor enlisted quarters and dining facility located at the northern portion of the base, along with a child development center at the southernmost part of the base (Figure 1). Because the region is crossed by numerous mapped fault strands and lies in close proximity to the 1999 Mw 7.1 Hector Mine earthquake rupture, NAVFAC thought it necessary to conduct geotechnical investigations of the area. As a student hire for NAVFAC, I conducted a morphotectonic analysis of the base using aerial imagery and topographic data in Google Earth to map the location of potentially active faults expressed in the geomorphology. The overall purpose of this investigation is to assure that no new building structures will be constructed atop faults that may produce rupture in the future, thus reducing hazardous conditions to those who would be occupying the buildings. Therefore, towards that end, I then compared my geomorphic observations on fault locations with other known information about the West Bullion and Mesquite Lake faults to determine whether any of these faults within the step-over may pose a threat to proposed or existing structures on base., San Diego State University
The bootstrap method for determining confidence level intervals of compositional data: A Visual Basic 6 program with graphical user interface
In the geological sciences it is normally impossible to obtain all the information needed to precisely calculate the mean, µ, and standard deviation, o-, of a given population. Hence, conventional statistical methods for determining these parameters involve collecting a random sample from the population. From this sample an estimate of the mean, X, and the standard deviation, s, are determined. The investigator then assumes that the actual distribution of the population follows a Student's t distribution. With this assumption in hand the 95% confidence interval is calculated from the relationship !critical* (s/ ✓n ). However, if the population does not follow a Student's tdistribution, then X ands may be in error. In contrast, in a typical bootstrap experiment the original data are used as an empirical distribution. This distribution is then randomly sampled a large number of times (e.g., 5000 times). During each resampling the mean is calculated, and the sampled data are returned to the original distribution. From such data the sampling distribution of the means is formed, and the 2.5 and 97.5 percentiles are precisely located. Hence, the bootstrap method for determining confidence level intervals is nonparametric and range preserving. Because of these properties it may prove more useful than classical parametric statistical methods, such as those based on the Student's t distribution. In an attempt to make such a process quick and efficient, a software program termed Bootstrapping the Uncertainties in Compositional Data was written in Visual Basic 6.0. The program allows users to (1) enter data in one of several formats, (2) calculate the 95% confidence level within seconds, and (3) view a frequency histogram of the resulting data., San Diego State University