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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Geological map of northern Rancho Agua Caliente Baja California, Mexico
Clay, quartz sand, clastic limestone, and a thick sec­tion of clay and very fine grained sand were deposited in the area of Northern Rancho Agua Caliente prior to late Cretaceous time. A hypabyssal intrusion of quartz monzon­ite caused the country rock to outward tilt and generally northwest trending faults along and parallel to the pluton borders, probably during the early part of Late Cretaceous time. Numerous dikes intrude the massive slate unit, some of these intrude the granitic rock, and a few cut the limestone and quartzite. With Late Cretaceous(?) isoclinal folding, small folds occurred in the plastic dikerock and foliation developed in the sedimentary rocks. A horizontal terrace of locally derived fluvial con­glomerate lies with angular unconformity on the metased­imentary sequence. These conglomerates, of probable Tertiary age, are separated by over one hundred feet of vertical movement along northwest-southeast trending faults which traverse the map area., San Diego State University
Geological reconnaissance of the central portion of the Palo Verde Mountains, Imperial County, California
The Palo Verde Mountains are located in the northeastern portion of Imperial County with the McCoy Mountains to the north and the Colorado River to the east. The Palo Verde Range trends northwest-southeast and is approximately 10 miles in length. Approximately 6000 feet of Tertiary volcanic rocks, highly variable in composition, predominate in the area. These sequences include andesites, dacites and tuff breccias. In the vicinity of Palo Verde Peak the younger volcanic rocks overlie the older volcanic rocks with a steep angular unconformity, both units having been strongly tilted. Limestone of Pliocene(?) age, unconformably above the principal volcanic rock units in the southeastern and eastern portions of the area. The area contains a network of faults none of which have more than 30 feet of displacement. Intense fracturing of the younger volcanics in the northern portions of the area is the major structural control relating to the hydrothermal manganese deposits. At least two periods of deformation affected the two Tertiary volcanic sequences. Sequences of limestone and shale with thicknesses on the order of about 75 to 100 feet, were deposited in a shallow marine extention of the Gulf of California., San Diego State University
Geology and paleontology of the playas de Tijauana, area, Northwestern Baja California, Mexico
Outcrops of fossiliferous gray to buff sandstone, similar to and contigous with characteristic rocks of the San Diego formation, unconformably overlife unammed eocene sandstones and Miocene? volcanic rocks west of the town of Tijuana in northwestern Baja California, Mexico. Fossils contained in the San Diego Formation indicate environments comparable to those found off San Diego today in a deep-inner sublittorial habitat. A cold water fauna found at the base of the section indicates upwelling of a greater intensity than found to occur today., San Diego State University
Geology and structural features of prebatholithic metamorphic rocks in the Valle Agua Amarga region, Bahia de los Angeles, Baja California,Mexico.
In the southernmost region of the Peninsular Ranges Batholith, prebatholithic rocks near Bahia de los Angeles comprise a steeply dipping, northwest striking package of schist and gneiss. Kilometer scale, grid mapping at 1:12,500 reveals four distinct protolith units: carbonate, volcanic+sedimentary, quartzite+conglomerate, and granite. The granite protolith, here designated the Cantera Gneiss, crops out over approximately 20 km2 as a pervasively sheared elongate body of granitic gneiss. The Cantera Gneiss has a prominent foliation and strongly developed mineral stretching lineation. The surrounding schist units have foliation and lineation fabrics concordant with the Cantera Gneiss, although the stretching lineation in these units is less prominent than in the gneiss. The sense of shear indicated by small scale structures at several localities is consistent with top to the west sense of displacement. Special attention to the measurements of the foliation and stretching lineation have provided us with a model to help determine the deformational history of the region. Petrographic analysis of samples document metamorphic mineral assemblages consistent with upper greenschist/lower amphibolite facies conditions of recrystallization. Micro structures including elongate crystal fabrics, mica fish structures and anastomosis can be seen in thin section and indicate sense of shear. Structural data were analyzed using the Stereonet 4.7a program which also confirms the continuity of the prominent fabric throughout the prebatholithic package. The structures of the metamorphic rocks in this region are consistent with major NNE-SSE compressional deformation. This shortening event is consistent with mid-Cretaceous east over west thrusting, documented along strike to the north in the Canon Calamajue region and further north in the southern San Pedro Martir region., San Diego State University
Geology of Lake Jennings area, San Diego County
The area is underlain by a roof pendant of metamorphic rocks, with north-south steep to vertical foliation and steep joints striking north-east and north-west. These are primarily metavolcanic and metasedimentary amphibolite, hornfels, quartzofeldspathic schists, gneiss and a transition zone of mixed rocks near the eastern contact with the pluton. Granodiorite and variable tonalites intrude the metamorphic rocks. A boulder conglomerate unconformably overlies these basement rocks in the east-central and west-central part of the area. Mappable lithologic units are plotted at a scale of 112,400 dovering an area of 4.1 square miles., San Diego State University
Geology of a plutonic-metamorphic terrain near Rancho Vallecitos, Northwestern Baja California, Mexico
A pre-mid Cretaceous sequence of sandstones, shales, limestones, and probable tuffs were first intruded by a granite pluton. Dacite and andesite dikes then intruded the pluton and the surrounding strata, and reached the surface as flows. Regional metamorphism was then imposed upon these rocks. Next a granodiorite pluton was emplaced, producing a contact meta­morphic aureole with a width of about 2000 feet. The intrusion of aplite and pegmatite dikes followed the granodiorite emplacement. Many of the streams in the area follow faults and frac­tures. The northwest trending normal faults follow regional trends, and give a linear character to many valleys. Where cutting metamorphic and plutonic contacts, the Calabazas Fault shows right lateral offset, and the Vallecitos Fault shows left lateral offset. A locally derived coarse boulder conglomerate rests on a high relief unconformity. This is overlain by a more mature cobble conglomerate of Eocene(?) age., San Diego State University
Geology of a portion of the Sweeney Pass and Carrizo Mountain 7 1/2 quadrangles
The Sweeney Pass area of southeastern San Diego County is underlain by the Julian Schist of probable Mississippian to Triassic age, and the early Late Cretaceous Stonewall Granodiorite and La Posta Quartz Diorite of the Peninsular Range Batholith. The conglomerates of the Split Mountain Formation and the volcanic rocks of the Alverson Canyon Formation were deposited nonconformably upon this crystal-line basement complex. The Pliocene Palm Spring Formation and Canebrake conglomerate, commonly associated with the sedimentary rock series of the Salton Basin, were only laid down over the northeastern part of the area. Three groups of faults were determined which control the attitudes of the rock units. The oldest, trending northeast, has not affected the miocene rocks and is probably Late Cretaceous or Eocene in are. North-trending faults in Carrizo Canyon and northwest-trending antithetic faults in the central and eastern parts have developed blocks tilted down on the eastern edge. The fault in Carrizo Canyon has a probably right-lateral slip component of 2,000 feet, and a dip-slip component of feet., San Diego State University
Geology of a portion of the area east of Rosarito Beach, Baja California
The area east of Rosarito Beach contains a sequence of rocks of Early Cretaceous to Pleistocene age. Slightly-metamorphosed volcanic rocks of the Alisitos Formation form the basement in the area. Late Cretaceous mudstone and sandstone of the Rosario Formation lie with angular discordance on the Alisitos Formation. Conglomerates of Formation A disconformably overlie the Rosario, and lie with angular discordance on the Alisitos. Sandstone and basalt of Formation B lie with angular discordance on the Alisitos and disconformably overlie the Rosario Formation and Formation A. Post-Formation B deformation has produced what appears to be an anticline with its axis trending north-westerly. The crest of the fold is about eight kilometers east of Rosarito Beach near the eastern border of the map area. The fold is defined in sandstone of Forma­tion B by westerly dips in the western part of the mapped area and easterly dips in the eastern part. The underlying Rosario Formation dips to the west on the western side of the anticlinal axis, and is not exposed or was not deposited in the area east of the axis., San Diego State University
Geology of a portion of the northern Sierra Juarez, Baja California Mexico
This report is of a previously unmapped 30 square mile area in a northern portion of the Sierra Juarez, Baja Calif­ornia, Mexico. The oldest rocks are a metamorphic series that includes quart-mica-schist, muscovite-quartz-phyllite, gneiss, quartzite and marble. They probably correspond to the Triassic(?) age Julian schist series in San Diego County, California. Tonalite was emplaced during Cretaceous(?) time, probably as at least three separate plutons. Two of these plutons assimilated part of the country rock, making a mixed rock unit which consists of two types of tonalite, metamorphic rocks, and an abundance of inclusions. Tonalite with a diff­erent composition than either of the tonalites in the mixed rocks has been mapped as a separate unit. Three sedimentary formations were deposited on the irre­gular, eroded surface of the metamorphic and plutonic rocks. Tertiary(?) age, Table Mountain Formation conglomerate is capping many of the metamorphic and plutonic rock hills, and extends down into the central valley of the mapped area. Late Cenozoic(?) siltstone and sandstone lie unconformably on the Table Mountain Formation in places in the valley. A lacustrine formation that probably formed within a depression in the sandstone facies of the siltstone and sandstone formation, is found in a limited area at the eastern edge of the sedimentary rocks. Pegmatites are abundant in the mixed rocks and metamorphic rocks, and less common in the tonalite. Several quartz veins, each several feet thick and more than one hundred feet long are located in the metamorphic rocks. The foliation and schistosity of the metamorphic rocks has a dominate northeast trend which suggests a northwest-southeast stress is responsible for some of the metamorphism. Contact metamorphism also probably influenced the character of these rocks. Marble is presently being mined to make cement, and it is possible economically profitable gold, tungsten, and quartz deposits will be developed or discovered and mined in the future., San Diego State University
Geology of an area 2 miles south of Romoland, Riverside County, California
At least 5000 feet of Triassic(?) marine meta-sed­iments crop out in a monadnock-like mass between the Perris and Menifee Valleys, Riverside County, California. Meta-quartzite and meta-feldspathic graywacke interbed­ded with a graduational section of slate, phyllite and schist form a northwest trending arcuate limb of a steep­ly plunging overturned syncline. Pelitic to fine grained rocks suggest relatively stable depositional conditions for 90 percent of the section. Rare, poorly sorted feldspathic meta-sandstone beds, rip up clasts, and flame structures indicate move­ment of sediment down a slope. Fossils found by Dr. M. A. Murphy of University of California at Riverside have been assigned a tentative Triassic age by Dr. E. C. Allison of San Diego State College and Dr. G. E. G. Westermann of McMaster Univer­sity, Ontario, Canada. These meta-sedimentary rocks, mapped as Bedford Canyon Formation by Larsen (1948), differ in age and lithology from the "flysch" type deposits described by Moscoso (1967) for the type locality of the Bedford Canyon Formation in the northern Santa Ana Mountains., San Diego State University
Geology of an area east of La Mision De San Miguel, Baja California
A thirty-three square mile area, east of La Mision de San Miguel, Baja California, was mapped on air photos at a scale of 1:35,700, The oldest formation is Mesozoic volcanic flow rock interbedded with well indurated epiclastic tuff breccias. These rocks are tilted at moderate angles to the southwest. An elongate one and one half mile long pluton of quartz diorite has intruded the volcanic and epiclastic rocks. Both Mesozoic volcanic and plutonic rocks are uncon­formably overlain by the Late Cretaceous Rosario Formation consisting of calcareous subgraywacke interbedded with mudstone and sandstone, with leaser proportions of conglomerate. The Rosario Formation is overlain in succession by Miocene(?) vesicular and porphyritic basalts, Miocene tuffaceous sandstone and marine feldspathic sandstone, and breccia which is either part of the Miocene sequence, or younger. The marine sandstone contains a twelve foot layer of diatomaceous earth. There are remnants of a stream terrace 50-100 feet above the present stream level. Fossils of the Rosario Formation include emmonites, baculites, echinoderm spines, three gastropod genera, nine pelecypod genera and a brachiopod. Undescribed fossils include limpets, and Lima-like clams. Miocene fossils include diatoms, radiolarians, the foraminifera Orbulina sp., other planktonic foreminifera, shark’ teeth, mammal and fish bones, the pelecypod Chione (Chionopsis) tembloreneis?, and the gastropods Turritella ocoyana and Terebra (Strioterebrum)? sp., San Diego State University
Geology of an area northeast of Rosarito Beach, Baja California, Mexico
The rocks in the map area are Cretaceous shales, Miocene volcanic rocks, and a Pliocene(?) conglomerate. The Miocene volcanic rocks, basalt flows and tuffaceous rocks, correlate to the lower part of the total Miocene volcanic section. The flows can be distinguished petrographically by their olivine content, their plagioclase composition, and the size of the plagioclase phenocrysts. The volcanic rocks are probably related to the Miocene volcanic rocks exposed in the Palos Verdes hills and surrounding areas. Post-Cretaceous deformation was followed by an episode of erosion, extrusion of the Miocene volcanic rocks, mild deformation of the Miocene rocks, partial truncation of the Miocene rocks, deposition of the Pliocene conglomerate, and uplift and subsequent erosion of the Pliocene conglomerate., San Diego State University

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