Thesis (doctoral)--Université de Paris, 1958.

Thesis (Ph. D.)--Bryn Mawr college, 1921. / Vita.

Thesis (Masters)--California Institute of Technology, 1928. / Advisor name found in thesis. Title from home page. Viewed 02/17/10. Includes bibliographical references.

<p> Two types of unusual concretions with similar contents but markedly different shapes and distributions were found in close stratigraphic proximity within the Whitmore Point Member of the Moenave Formation. Roughly cylindrical, elongate concretions were found in parallel and regularly spaced rows, and a layer of irregularly shaped and distributed fossiliferous concretions was discovered only a few centimeters above the cylindrical concretions. Both sets of concretions contain abundant hematite as well as enameloid fish scales. In addition, the concretions contain numerous ostracod carapaces and what appear to be rip-up clasts. Microprobe and Raman analyses of representative concretion samples reveal that the cylindrical concretions have a groundmass largely composed of silica while the irregular concretions have a groundmass largely composed of dolomite, and the ostracods within each type of concretion have been altered and match the chemistry of the surrounding groundmass. Evidence of multiple cement precipitation events is present within each concretion. These unusual concretions suggest mass fish mortality events in the large lake that occupied the St. George area in the early Jurassic.</p>

No description available.

No description available.

No description available.

A reconnaissance of sediments containing radiolarians was performed for localities along Baja California and Tres Marias Islands. Only seven land-base sections (El Cien, Tortugas, Arroyo Tiburon, Cabo San Lucas-La Paz, San Felipe, Arroyo Hondo and Maria Cleofas) together with Experimental Mohole (the only offshore site) were considered worthy of pursuit in this study. The most significant siliceous deposition in the selected sections occurs during the Didymocyrtis antepenultima Zone (between 10.1 and 8.8 m.y.a.). This interval is also the major period of formation of siliceous rock sequences in California. All the sections studied herein are correlative with the tropical radiolarian zonation of Riedel and Sanfilippo (1978), and exhibit very little to poor correlation with the cold water radiolarian biofacies of Weaver et al. (1981). A refinement of Casey's hypothetical ocean (Casey et al., 1982) and his biogeographic categories was utilized in the paleoceanographic interpretation herein. The quantitative analyses of the sections provided enough samples to reconstruct the paleoceanography of the study area at two time intervals. The first one at 10 m.y.a., shows the intense development of a paleo-El Nino Current, producing high percentages of warm water radiolarians in all the basins. However, Arroyo Tiburon might have been influenced by the paleo-California Current, causing obstacle upwelling in this basin. The second reconstruction at 8.8 m.y.a. suggests that the opening of the Gulf of California occurred at that time, originating an oceanic front that could influence the movement of the paleo-California Current. This reconstruction (8.8 m.y.a.) showed a time slice of high upwelling conditions, where the paleo-California Current probably had a wide path, producing obstacle upwelling in the Vizcaino Peninsula, but the southernmost sections (Tres Marias Islands and Cabo San Lucas-La Paz) were mostly influenced by eastern tropical waters. In addition, partial synonomies of the radiolarians identified (including notes on their paleoecological considerations) and the radiolarian barren localities are given as Appendices I and II respectively.

Species (single lineages) of two clades (extended lineages) of the polycystine radiolarian subfamily Artiscinae were studied to determine their pattern of evolutionary change in Miocene tropical pelagic sediments. Morphometric measurements were made on specimens from 43 closely-spaced samples from a continuous stratigraphic sequence in DSDP core 9-77B, eastern equatorial Pacific. The samples are at approximately 165,000 year intervals through a 7.1 m.y. period. For this study, a new method of biosystematic analysis was formulated to deal with fossil organisms that are suspected to exhibit gradual anagenetic change through time. Three types of lineages and three types of extinction are defined to enable unequivocal interpretation of evolutionary processes and patterns. Evolution in the artiscins is both punctuated and gradual: the Ommatartus tetrathalamus clade and the O. hughesi clad both contain gradually-changing characters, but in both clades descendants are separated from ancestors by cladogenetic events and the appearance of apomorphic characters. Other characters reveal stasis. Previous authors arbitrarily subdivided single continuous characters undergoing anagenesis to delimit artiscin species, but this practice is typological and ignores species variability and important apomorphic characters. For these reasons, the species Cannartus laticonus and O. antepenultimus are synonymized with O. penultimus. Furthermore, the character of polar caps is not homologous between the two artiscin lineages; in the O. hugesi lineage, caps develop from the spongy column, not as an extension of the cortical shell. Since anagenetic phyletic change in the artiscins controls macroevolutionary change to an extent equal to cladogenetic punctuated change, there is no reason to adopt a punctuated model over a gradual one for this taxon. However, artiscin classification must be radically revised in light of the monophyletic lineages (clades) delimited by cladistic analysis. Furthermore, the implications of this study make clear the necessity to rely solely on material, non-evolutionary data for biostratigraphic purposes. Lineage-zones and phyletic-biohorizons are invalid because they require a specific evolutionary model and method of phylogenetic inference, neither of which can apriorily be assumed to be correct.

Detailed stratigraphic and sedimentologic study of outcrop exposures of the Pt. Lookout Fm. and adjacent Mancos and Menefee Fms. of the southeastern San Juan Basin served as the basis of research, whose objectives were to (1) document the small scale facies patterns within the nearshore marine Pt. Lookout Sandstone (2) relate sediment textural characteristics to corresponding environments of deposition, and (3) define factors influencing progradation of the NW-SE trending Pt. Lookout strandline. Five major depositional environments preserved in the progradational sequence are: Offshore Transition Zone (Facies I); Shoreface/Delta Front (Facies II); Foreshore (Facies III); Lower Coastal/Delta Plain (Facies IV); and Upper Coastal/Delta Plain (Facies V). The distribution of these facies reflects interaction of relatively low wave energy, moderate tidal strength, and locally moderate fluvial input along the studied portion of the ancient coastline. Combination of these processes resulted in development of a low wave-energy mainland beach separating an extensive tidal creek complex from the open marine. Where tidal creeks experienced fluvial connection, a dip-aligned delta prograded. Textural parameters (particularly the position of modal population, constancy of the mode, and standard deviation of the sample) successfully distinguish lower shoreface, upper shoreface, delta front/estaurine, and fluvial sandstones. Results suggest that vertical textural progressions may be a useful diagnostic tool in ancient sandstones, including those for which the total range in grain size is narrow and which display diagenetic complications. Regression of the strandline occurred in response to seaward stacking of small, asymmetric fourth-order transgressive-regressive cycles. A model of basinwide progradation predicts broad limits of 17,000 to 66,000 years for fourth-order cycle duration, reflecting probable climatic impact within the basin. Maximum calculated sedimentation rate (0.4m/1000 years) documents relative isolation of the area from tectonically-induced subsidence characteristic of the western U.S. fold-thrust belt. The relative impact of sediment supply-vs-submergence in shaping the strandline migration pattern appears discernible within the geometry of the fourth-order cycles. Although unresolvable in larger cycles, the thickness of fourth-order cycles may separate the factors of sediment supply and submergence controlling shoreline stability through time.