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Kristin McDougall

Publications and source records attributed to Kristin McDougall.

14 recordsLinked to original sources
USGS2017

The U.S. Geological Survey Flagstaff Science Campus—Providing expertise on planetary science, ecology, water resources, geologic processes, and human interactions with the Earth

T he U.S. Geological Survey’s Flagstaff Science Campus is focused on interdisciplinary study of the Earth and solar system, and has the scientific expertise to detect early environmental changes and provide strategies to minimize possible adverse effects on humanity. The Flagstaff Science Campus (FSC) is located in Flagstaff, Arizona, which is situated in the northern part of the State, home to a wide variety of landscapes and natural resources, including (1) young volcanoes in the San Francisco Volcanic Field, (2) the seven ecological life zones of the San Francisco Peaks, (3) the extensive geologic record of the Colorado Plateau and Grand Canyon, (4) the Colorado River and its perennial, ephemeral, and intermittent tributaries, and (5) a multitude of canyons, mountains, arroyos, and plains. More than 200 scientists, technicians, and support staff provide research, monitoring, and technical advancements in planetary geology and mapping, biology and ecology, Earth-based geology, hydrology, and changing climate and landscapes. Scientists at the FSC work in collaboration with multiple State, Federal, Tribal, municipal, and academic partners to address regional, national, and global environmental issues, and provide scientific outreach to the general public.

Arizona↗
USGS2017

The Neogene genus Streptochilus (Brönnimann and Resig, 1971) from the Gulf of California

Four species of the planktonic foraminiferal genus Streptochilus from key Neogene marine localities are documented in relation to the evolution of the Gulf of California: S. globigerus , S. latus , S. macdougallae sp. nov., and S. inglei sp. nov. Planktonic foraminiferal bioevents and strontium isotopes in the Bouse, Tirabuzón, Carmen and Ojo de Buey lithostratigraphic units constrain the local distribution range between 6 and 5.3 Ma for the last three species, whereas S. globigerus appears locally at 5.5 Ma and disappears between 3.79 and 3.46 Ma in the Imperial and Trinidad Formations. The last occurrence of Streptochilus latus , and the first and last occurrences of S. globigerus in the ancient Gulf of California are correlated with bioevents calibrated in the equatorial Pacific; therefore, they can be used as reliable local biostratigraphic markers. The presence of Streptochilus in the ancient Gulf of California seems to correlate with upwelling, in a pattern similar to that observed in the modern oceans.

Gulf of California↗
USGS2014

Evidence for a marine incursion along the lower Colorado River corridor

Foraminiferal assemblages in the stratigraphically lower part of the Bouse Formation in the Blythe Basin indicate marine conditions whereas assemblages in the upper part of the Bouse Formation indicate lacustrine conditions and suggest the presence of a saline lake. Benthic foraminiferal assemblages in the lower part of the Bouse Formation are similar to lagoonal and inner neritic biofacies of the modern Gulf of California. Evidence suggesting a change from marine to lacustrine conditions includes the highest occurrence of planktic foraminifers at an elevation of 123 m asl, the change from low diversity to monospecific foraminiferal assemblages composed only of Ammonia beccarii (between 110 to126 m asl), an increase in abundance of A. beccarii specimens (above ~110 m asl), increased number of deformed tests (above ~123 m asl), first appearance of Chara (at ~85 m asl), lowest occurrence of reworked Cretaceous coccoliths (at ~110 m), a decrease in strontium isotopic values (between 70-120 m), and δ 18 O and δ 13 C values similar to sea water (between 70-100 m asl). Planktic foraminifers indicate a late Miocene age between 8.10 and 5.3 Ma for the oldest part of the Bouse Formation in the southern part of the Blythe Basin. Benthic and planktic foraminifers correlate with other late Miocene sections and suggest that the basal Bouse Formation in the Blythe Basin was deposited at the northern end of the proto-Gulf of California. After the marine connection was restricted or eliminated, the Colorado River flowed into the Blythe Basin forming a saline lake. This lake supported a monospecific foraminiferal assemblage of A. beccarii until the lake spilled into the Salton Trough and the Colorado River became a through-flowing river.

California↗
USGS2014

Geologic and geophysical maps of the eastern three-fourths of the Cambria 30' x 60' quadrangle, central California Coast Ranges

The Cambria 30´ x 60´ quadrangle comprises southwestern Monterey County and northwestern San Luis Obispo County. The land area includes rugged mountains of the Santa Lucia Range extending from the northwest to the southeast part of the map; the southern part of the Big Sur coast in the northwest; broad marine terraces along the southwest coast; and broadvalleys, rolling hills, and modest mountains in the northeast. This report contains geologic, gravity anomaly, and aeromagnetic anomaly maps of the eastern three-fourths of the 1:100,000-scale Cambria quadrangle and the associated geologic and geophysical databases (ArcMap databases), as well as complete descriptions of the geologic map units and the structural relations in the mapped area. A cross section is based on both the geologic map and potential-field geophysical data. The maps are presented as an interactive, multilayer PDF, rather than more traditional pre-formatted map-sheet PDFs. Various geologic, geophysical, paleontological, and base map elements are placed on separate layers, which allows the user to combine elements interactively to create map views beyond the traditional map sheets. Four traditional map sheets (geologic map, gravity map, aeromagnetic map, paleontological locality map) are easily compiled by choosing the associated data layers or by choosing the desired map under Bookmarks.

California↗
USGS2014

Digital database of microfossil localities in Alameda and Contra Costa Counties, California

The eastern San Francisco Bay region (Contra Costa and Alameda Counties, California) is a geologically complex area divided by faults into a suite of tectonic blocks. Each block contains a unique stratigraphic sequence of Tertiary sediments that in most blocks unconformably overlie Mesozoic sediments. Age and environmental interpretations based on analysis of microfossil assemblages are key factors in interpreting geologic history, structure, and correlation of each block. Much of this data, however, is distributed in unpublished internal reports and memos, and is generally unavailable to the geologic community. In this report the U.S. Geological Survey microfossil data from the Tertiary sediments of Alameda and Contra Costa counties are analyzed and presented in a digital database, which provides a user-friendly summary of the micropaleontologic data, locality information, and biostratigraphic and ecologic interpretations.

California↗
USGS2013

Superimposed extension and shortening in the southern Salinas Basin and La Panza Range, California: A guide to Neogene deformation in the Salinian block of the central California Coast Ranges

We synthesized data from geologic maps, wells, seismic-reflection profiles, potential-field interpretations, and low-temperature thermochronology to refine our understanding of late Cenozoic extension and shortening in the Salinian block of the central California Coast Ranges. Data from the La Panza Range and southern Salinas Basin document early to middle Miocene extension, followed by Pliocene and younger shortening after a period of little deformation in the late Miocene. Extension took place on high-angle normal faults that accommodated ∼2% strain at the scale of the ∼50-km-wide Salinian block (oriented perpendicular to the San Andreas fault). Shortening was accommodated by new reverse faults, reactivation of older normal faults, and strike-slip faulting that resulted in a map-view change in the width of the Salinian block. The overall magnitude of shortening was ∼10% strain, roughly 4–5 times greater than the amount of extension. The timing and magnitude of deformation in our study area are comparable to that documented in other Salinian block basins, and we suggest that the entire block deformed in a similar manner over a similar time span. The timing and relative magnitude of extension and shortening may be understood in the context of central Coast Range tectonic boundary conditions linked to rotation of the western Transverse Ranges at the south end of the Salinian block. Older models for Coast Range shortening based on balanced fault-bend fold-style cross sections are a poor approximation of Salinian block deformation, and may lead to mechanically improbable fault geometries that overestimate the amount of shortening.

California↗
USGS2012

Paleontology and geochronology of the Long Beach core sites and monitoring wells, Long Beach, California

The U.S. Geological Survey's Focus on Quaternary Stratigraphy in Los Angeles (FOQUS-LA) project was a cooperative coring program between Federal, State, and local agencies. It was designed to provide a better understanding of earthquake potentials and to develop a stratigraphic model of the western Los Angeles Basin in California. The biostratigraphic, geochronologic, and paleoecologic analyses of eight wells drilled during the FOQUS-LA project are presented. These analyses are based on microfossils (benthic and planktic foraminifers), macrofossils, paleomagnetic stratigraphy, optically stimulated luminescence, thermoluminescence, radiocarbon dating, and tephrochronology. A geochronologic framework (incorporating paleomagnetism, luminescence, and tephrochronology) was used to calibrate the sequence stratigraphic units in the FOQUS-LA wells and also was used to calibrate the ages of the microfossil stage and zonal boundaries. The results of this study show that (1) the offshore California margin zones can be used in a nearshore setting, and (2) the California margin zonal scheme refines the chronostratigraphic resolution of the benthic foraminiferal biostratigraphic framework for the Pacific Coast. Benthic foraminiferal stages are modified by the recognition of an early Hallian substage, which is a faunal change recognized throughout the Los Angeles Basin. Although no detailed macrofossil zonations exist for the Quaternary of southern California, several species, whose distribution is regulated by the climatic conditions, are useful as secondary marker species in the shallower water deposits of the Los Angeles Basin.

California↗
USGS2008

Newly discovered Paleocene and Eocene rocks near Fairfield, California, and correlation with rocks in Vaca Valley and the so-called Martinez Formation or Stage

Discovery of a 3-foot thick sandstone bed with abundant Turritellid gastropods of late Paleocene age about 4 miles northeast of Fairfield and on the southwest flank of Cement Hill, Solano County provides an opportunity to reevaluate the relationships of lower Tertiary formations in this part of California. Cement Hill is named for travertine deposits in and on top of sandstone of Late Cretaceous age. In this report, the current study area where the Paleocene fossils were recently discovered is referred to as lower Cement Hill and is located in section 7 of the U.S. Geological Survey Fairfield North 7.5-minute quadrangle, Township 5 North, Range 1 West. Lower Cement Hill is about 23 miles north of the so-called Martinez 'formation' or stage area (Weaver and others, 1941) of late Paleocene age near Martinez. The Martinez 'formation' and stage have played a significant role in the development of early Tertiary stratigraphy in this part of California. The discovery of correlative rocks at Cement Hill was unsuspected and may be helpful in defining the extent of this so-called formation or stage. Coccolith identification and correlations are by David Bukry, foraminifer identifications and correlations by Alvin Almgren and Kristin McDougall, gastropod identification and correlation by LouElla Saul, and Radiolaria identifications and correlations are by Annika Sanfilippo.

California↗
USGS2008

California Cenozoic Biostratigraphy -- Paleogene: Chapter 4 in Petroleum systems and geologic assessment of oil and gas in the San Joaquin Basin Province, California

The time transgressive nature of the California benthic foraminiferal stages is in most cases the result of poor taxonomy, use of local species ranges, and a lack of understanding about the type sections. Correcting these problems allows the stages to be consistently applied and enhances their ability to identify coeval strata. Each stage is identified by the first and last appearances of selected cosmopolitan benthic foraminiferal species and of reliable local species. Although further study is needed, the stages correlate with the international time scale. The revised age interpretation of the stages suggests that the Cheneyian Stage is coeval with planktic zone P1 through P3, the Ynezian Stage is coeval with planktic zone P4, the Bulitian Stage is missing in most section but when present is coeval with zones P5 and P6a, the Penutian Stage is coeval with planktic zones P6b through early P9 (no younger than the overlap between P9 and CP11), the Ulatisian Stage is coeval with P9 (younger than CP11) through P11, the Narizian Stage is coeval with zones P12 through P15, and the Refugian Stage is coeval with zones P16 and P17.

California↗
USGS1980

Paleoecological evaluation of Late Eocene biostratigraphic zonations of the Pacific Coast of North America

The late Eocene zonal criteria of the west coast of North America are to a large extent controlled by paleoecology and, therefore, the correlation of coeval but environmentally different benthic foraminiferal faunas cannot be achieved before paleoecological control of the biostratigraphy is understood. The faunal trends, morphology, characteristic occurrences and estimated upper depth limits of the benthic foraminifers and associated microfossils in the Oregon and Washington study sections lead to the recognition of paleoecologic facies. The interpretation of these late Eocene facies as bathymetric and low-oxygen facies is based on analogous late Eocene and Holocene assemblages. The paleoecologic facies criteria are often identical to the stage and zonal criteria. In the California zonal schemes, the Narizian zones are identified by lower and middle bathyal faunas whereas the Refugian zones are identified by outer neritic and upper bathyal faunas. The Washington late Eocene zones are identified by middle bathyal and transported neritic faunas. Modifications of the existing zonal schemes such that time and not paleoecology is the controlling factor results in a zonation that synthesizes the existing zonal schemes, recognizes regional stratigraphic ranges of diagnostic species, and removes paleoecologically controlled species occurrences. The late Narizian encompasses a bathyal and a neritic facies. The bathyal facies is correlative with a modified Bulimina corrugata Zone of California and the Uvigerina cf. U. yazooensis Zone of Washington. The neritic late Narizian facies corresponds to a modified Bulimina schencki-Plectofrondicularia cf. P. jenkinsi Zone of Washington and a modified Amphimorphina jenkinsi Zone of California. The Refugian can also be divided into a neritic and a bathyal facies. Although the early and late subdivisions of this stage are tentative, the early Refugian is equivalent to the modified versions of the Cibicides haydoni and the Uvigerina atwilli Subzones of the Valvulineria tumeyensis Zone and the Uvigerina vicksburgensis Zone (in part) of California and the modified version of the Sigmomorphina schencki Zone of Washington. The late Refugian is equivalent to modified versions of the California Uvigerina vicksburgensis Zone (in part) and the Washington Cassidulina galvinensis Zone. The Cibicides haydoni Subzone is the neritic facies of the Refugian Stage, whereas the faunas of the Uvigerina atwilli Subzone and the Uvigerina vicksburgensis, Sigmomorphina schencki and Cassidulina galvinensis Zones represent the bathyal Refugian facies.

Paleontological Monograph↗