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Long Dormancy, Low Slip Rate, And Similar Slip‐Per‐Event For The Emerson Fault, Eastern California Shear Zone, Charles M. Rubin, Kerry Sieh Jul 1997

Long Dormancy, Low Slip Rate, And Similar Slip‐Per‐Event For The Emerson Fault, Eastern California Shear Zone, Charles M. Rubin, Kerry Sieh

All Faculty Scholarship for the College of the Sciences

Excavations in a playa along the 1992 rupture of the Emerson fault reveal evidence of two paleoseismic events, with only one large prehistoric rupture in the past 15 millennia. Accelerator mass spectrometer radiocarbon ages of charcoal from playa sediments and from fault‐scarp colluvium directly beneath the playa beds indicate that the last large prehistoric slip event occurred about 9000 ka. Trench‐wall exposures revealed clear evidence of at least one pre‐9 ka rupture at the playa site. The event horizon of this earthquake is between two pedogenic carbonate layers that have radiocarbon ages of 14.8 ka and 24.1 ka, implying that …


Post-Middle Miocene Geologic History Of The Tualatin Basin, Oregon With Hydrogeologic Implications, Doyle Coley Wilson May 1997

Post-Middle Miocene Geologic History Of The Tualatin Basin, Oregon With Hydrogeologic Implications, Doyle Coley Wilson

Dissertations and Theses

The geologic history and sedimentary till of the Tualatin Basin after Columbia River Basalt Group (CRBG) emplacement is assessed and related to groundwater characteristics. The 334 m deep HBD-1 core from the Hillsboro Airport, provides the primary information for sediment characterization and is supported by over 2400 well logs and cores, and four seismic lines. The sedimentary section above the 26 m thick paleosol on the CRBG in HBD-I is divided into two main groups: a 25 m thick section of Missoula flood sediments called the Willamette Silt overlies a 263 m thick finegrained sequence of fluvial Neogene sediments.

Pollen, …


40Ar/39 Ar Geochronology Of The Lowland Creek Volcanic Field And Its Temporal Relations With Other Eocene Volcanic Areas, Vladimir Olegovich Ispolatov Apr 1997

40Ar/39 Ar Geochronology Of The Lowland Creek Volcanic Field And Its Temporal Relations With Other Eocene Volcanic Areas, Vladimir Olegovich Ispolatov

OES Theses and Dissertations

Exposures of the Eocene Lowland Creek Volcanics (LCV) cover an area of 2000 km2 in southwestern Montana, and consist of basal elastic deposits, felsic tuffs, and felsic and intermediate lavas with an aggregate thickness of about 2 km. New 40Ar/39Ar dates show that volcanic activity lasted for at least 4.2 million years (52.7- 48.5 Ma), or even longer (4.5-4.7 million years: from 53.0-53.2 Ma to 48.5 Ma). During evolution of the volcanic field, early explosive volcanism was gradually replaced by extrusive activity. During the transition period (52.7-51.5 Ma), the two volcanic styles coexisted.

The evolution of …


Grand Tour-Part 2: Petrogenesis And Thermal Evolution Of Deep Continental-Crust: The Record From The East Humboldt Range, Nevada, Allen J. Mcgrew, Mark T. Peters Jan 1997

Grand Tour-Part 2: Petrogenesis And Thermal Evolution Of Deep Continental-Crust: The Record From The East Humboldt Range, Nevada, Allen J. Mcgrew, Mark T. Peters

Department of Earth, Environment and Sustainability Faculty Publications

The northern part of the East Humboldt Range, Nevada, provides a rare opportunity to explore the petrogenetic environment of deep levels in the middle crust during both large-scale Mesozoic contraction and Cenozoic regional extension. On this segment of the field trip, we will explore evidence bearing on the character of the metamorphic and magmatic history of this terrane, and attempt to link these constraints to the rheology and tectonic evolution of the middle crust during the Mesozoic and Cenozoic.


The Grand Tour Of The Ruby-East Humboldt Metamorphic Core Complex, Northeastern Nevada: Part 1-Introduction & Road Log, Arthur W. Snoke, Keith A. Howard, Allen J. Mcgrew, Bradford R. Burton, Calvin G. Barnes, Mark T. Peters, James E. Wright Jan 1997

The Grand Tour Of The Ruby-East Humboldt Metamorphic Core Complex, Northeastern Nevada: Part 1-Introduction & Road Log, Arthur W. Snoke, Keith A. Howard, Allen J. Mcgrew, Bradford R. Burton, Calvin G. Barnes, Mark T. Peters, James E. Wright

Department of Earth, Environment and Sustainability Faculty Publications

The purpose of this geological excursion is to provide an overview of the multiphase developmental history of the Ruby Mountains and East Humboldt Range, northeastern Nevada. Although these mountain ranges are commonly cited as a classic example of a Cordilleran metamorphic core complex developed through large-magnitude, mid-Tertiary crustal extension, a preceding polyphase Mesozoic contractional history is also well preserved in the ranges. An early phase of this history involved Late Jurassic two-mica granitic magmatism, high-temperature but relatively low-pressure metamorphism, and polyphase deformation in the central Ruby Mountains. In the northern Ruby Mountains and East Humboldt Range, a Late Cretaceous history …


Hydrochemical Definition Of Ground Water And Surface Water, With An Emphasis On The Origin Of The Ground-Water Salinity In Southern Juab Valley, Juab County, Utah, Heidi K. Hadley May 1996

Hydrochemical Definition Of Ground Water And Surface Water, With An Emphasis On The Origin Of The Ground-Water Salinity In Southern Juab Valley, Juab County, Utah, Heidi K. Hadley

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

As part of a U.S. Geological Survey study in Juab Valley in central Utah from 1991 to 1994, the chemistry of ground - and surface -water samples was determined. Total dissolved solids in the ground water of southern Juab Valley have historically been higher, in general, than ground water in other areas of Utah. Total dissolved solids for ground-water samples from this study ranged from 623 to 3,980 milligrams/liter. High-sulfate chemical data of previous studies suggested that the major source of ground-water salinity is the dissolution of gypsum (hydrous calcium sulfate ) from the Arapien Shale. Sulfur-34 to sulfur-32 isotopic …


Geology Beneath The Primary Management Systems Evaluation Area (Msea) Site Southwest Of Shelton, Buffalo County, Nebraska, Robert F. Diffendal Jr., Frank A. Smith Feb 1996

Geology Beneath The Primary Management Systems Evaluation Area (Msea) Site Southwest Of Shelton, Buffalo County, Nebraska, Robert F. Diffendal Jr., Frank A. Smith

Robert F. Diffendal, Jr., Publications

In 1990, as part of a national presidential initiative on water quality, researchers from the University of Nebraska–Lincoln (UNL) Institute of Agriculture and Natural Resources (IANR) received a multiyear grant from the U.S. Department of Agriculture, Cooperative State Research Service, to study management of irrigated corn and soybeans to minimize groundwater contamination. D. G. Watts, R. F. Spalding, and J.S. Schepers, of the IANR led a study at one of the Management Systems Evaluation Areas (MSEA). This area was made up of two sites, a primary site on a terrace of the Platte River near Shelton and a secondary site …


Geology Beneath The Primary Management Systems Evaluation Area (Msea) Site Southwest Of Shelton, Buffalo County, Nebraska, Robert F. Diffendal Jr., Frank A. Smith Feb 1996

Geology Beneath The Primary Management Systems Evaluation Area (Msea) Site Southwest Of Shelton, Buffalo County, Nebraska, Robert F. Diffendal Jr., Frank A. Smith

Department of Earth and Atmospheric Sciences: Faculty Publications

In 1990, as part of a national presidential initiative on water quality, researchers from the University of Nebraska-Lincoln (UNL) Institute of Agriculture and Natural Resources (IANR) received a multi-year grant from the United States Department of Agriculture, Cooperative State Research Service, to study management of irrigated com and soybeans to minimize groundwater contamination. D.G. Watts, R.F. Spalding, and J.S. Schepers, of the IANR led a study at one of the Management Systems Evaluation Areas (MSEA). This area was made up of two sites, a primary site on a terrace of the Platte River near Shelton and a secondary site nearer …


A Field Trip Guide To Sites Of Geological Interest, Western New Providence Island, Bahamas, James L. Carew, H. Allen Curran, John E. Mylroie, Neil E. Sealey, Brian White Jan 1996

A Field Trip Guide To Sites Of Geological Interest, Western New Providence Island, Bahamas, James L. Carew, H. Allen Curran, John E. Mylroie, Neil E. Sealey, Brian White

Geosciences: Faculty Publications

See other Smith authored Field Trip Guides of Gerace Research Center.


The Middle And Upper Ordovician Bioclastic Carbonate ("Trenton") Play In The Appalachian Basin, Brandon C. Nuttall Jan 1996

The Middle And Upper Ordovician Bioclastic Carbonate ("Trenton") Play In The Appalachian Basin, Brandon C. Nuttall

Information Circular--KGS

The bioclastic carbonate play in the Appalachian Basin (referred to by drillers as the "Trenton") includes both gas and oil produced from Middle and Upper Ordovician stratigraphic and combination traps in linear reservoirs often mistaken for reefs. While production from this play is currently reported from nine fields in south-central and eastern Kentucky and five fields in New York, potential reservoir rocks are present throughout most of the Appalachian Basin from New York to Tennessee. Along the western flank of the Appalachian Basin, in the Blue Grass Region of central Kentucky, Middle and Upper Ordovician strata crop out. In the …


The Geology Of Parrett Mountain, Oregon, And Its Influences On The Local Groundwater Systems, Brett Todd Brodersen Sep 1994

The Geology Of Parrett Mountain, Oregon, And Its Influences On The Local Groundwater Systems, Brett Todd Brodersen

Dissertations and Theses

A geologic study of the Parrett Mountain area, located twenty miles (32 kms) south-southwest of Portland, Oregon, was initiated by the Oregon Water Resources Department. The main goal was to create a stratigraphic and structural model of Parrett Mountain in order to better understand the local basalt aquifers present there.

Previous geologic studies of the area revealed the mountain to be composed of Columbia River basalt. Field mapping and hand lithologic and geochemical analyses allowed the basalt to be subdivided into eleven basalt flows. These flows are as follows: (from oldest to youngest) the Wapshilla Ridge (WpR), the Ortley-Grouse Creek …


The Relationship Between Basement Structure And Overlying Sediments In The Michigan Basin: A Detailed Gravity Investigation, Mitchell Joseph Gutaj Apr 1994

The Relationship Between Basement Structure And Overlying Sediments In The Michigan Basin: A Detailed Gravity Investigation, Mitchell Joseph Gutaj

Masters Theses

A detailed gravity study consisting of 945 measurements was carried out in Branch County, Michigan. The objectives of this study are to determine if: (a) structural trends interpreted from regional gravity data in southwestern Michigan are also observed in a more detailed survey in Branch County and (b) any relationship exists between observed geophysical anomalies, geological structures and overlying basin sediments.

The resulting gravity map indicates that NW-SE, NE-SW, and N-S trends are more clearly identified comprising several elliptical highs and lows. Variations in the isopachs of some of the overlying Phanerozoic formations area are also coincident with gravity anomalies. …


Hydrogeology And Hydrochemistry Of The Delta Wadi El-Arish Area Sinai Peninsula, Egypt, Medhat A. El-Bihery May 1993

Hydrogeology And Hydrochemistry Of The Delta Wadi El-Arish Area Sinai Peninsula, Egypt, Medhat A. El-Bihery

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Delta Wadi El-Arish, Sinai Peninsula, Egypt, forms one of the most important parts of Egypt for industrial and agricultural expansion projects. This study focuses on the hydrogeology and the hydrochemistry of the Quaternary aquifer in the delta Wadi El-Arish area. Accurate information about the groundwater characteristics of the Quaternary aquifer will allow implementation of a sound water management policy for the Wadi El-Arish area.

The objectives of this study include: 1) determining the relationships between groundwater extraction and water levels and water quality using water-level measurements, total extraction of the wells, and chemical analyses of water samples; 2) determining the …


Application Of Sealevel Stratigraphy To Neogene Great Plains Stratigraphy, Robert F. Diffendal Jr., A. Lowrie Jan 1993

Application Of Sealevel Stratigraphy To Neogene Great Plains Stratigraphy, Robert F. Diffendal Jr., A. Lowrie

Robert F. Diffendal, Jr., Publications

Absolute-dated high frequency (Milankovitch cycles) marine climate/sealevel oscillatory stratigraphy can be correlated generally with continental stratigraphies. Improvements in absolute dating of Neogene formations across the North American Great Plains make this a candidate area in which to correlate marine and continental stratigraphies. Mid-latitude continental areas respond directly to climate variations. During glaciated/ cold climates, sealevel lowering results in steepened river gradients, increased erosion all along the river channel, and larger stress-bed loads. This, combined with glacial catastrophic flooding, produces greater cut-and-fill sequences along river systems than crevasse splays along the emergent coastal plain, deltas along the shelf, and submarine fans …


Fluid Inclusion Studies Of The Morefield Pegmatite Amelia County, Virginia, John Richard Smerekanicz Oct 1992

Fluid Inclusion Studies Of The Morefield Pegmatite Amelia County, Virginia, John Richard Smerekanicz

OES Theses and Dissertations

The Morefield Pegmatite is a planar, nearly vertical body situated in Grenville age gneisses and schists in the southeast Piedmont of Virginia. It consists of a mineralogically simple albite-quartz outer zone and a texturally and mineralogically complex inner zone of microcline-topaz-quartz, with trace amounts of rare-element minerals. Fluid inclusions in samples of quartz, topaz, beryl, spessartite and albite that span the length, width and depth of both zones can be classified by chemical composition into two main groups: H2O-rich solutions and CO2- H2O -rich fluids. The H2O -rich inclusions consist of H …


Ground Water Investigation Of The Petersburg Granite In Chesterfield County, Virginia, Michael W. Bennett Oct 1992

Ground Water Investigation Of The Petersburg Granite In Chesterfield County, Virginia, Michael W. Bennett

OES Theses and Dissertations

Yields of new water wells in areas underlain by the Petersburg Granite in Chesterfield County, Virginia should improve if procedures for site selection and well construction follow the new guidelines proposed. These guidelines integrate analyses of aerial photo linears and drainage patterns, survey of bedrock joints and shallow geophysical properties and techniques using several statistical methods.

Throughout the study area, fracture traces form in nearly the same orientation as bedrock fractures. The dominant N-S and E-W trending bedrock joints also corresponded to aerial photo linears of similar orientation.

Across one large fracture zone, both gamma-ray and electrical resistivity surveys reveal …


Stable Isotope Composition Of Calcareous Paleosols And Ground-Water Cements From The Ogallala Group (Neogene), Western Nebraska, Leonard Robert Gardner, Robert F. Diffendal Jr., Douglas F. Williams May 1992

Stable Isotope Composition Of Calcareous Paleosols And Ground-Water Cements From The Ogallala Group (Neogene), Western Nebraska, Leonard Robert Gardner, Robert F. Diffendal Jr., Douglas F. Williams

Robert F. Diffendal, Jr., Publications

A preliminary survey has been made of the stable isotope composition of secondary carbonates in the Ogallala Group of western Nebraska. The purpose of the study was to ascertain whether the isotopic signatures of calcareous paleosols in the fine grained facies of the Ogallala and groundwater cements in gravel facies might provide a basis for stratigraphic correlation and/or paleoclimatic interpretation.

The groundwater cemented channel gravels are modestly depicted in IRO (δ18O = –10‰) as compared to calcareous paleo'sols (δ18O = –8.0 to –9.0‰). Gravels of different age, however, have essentially identical isotopic signatures. The isotopic variability …


Stratigraphic And Structural Framework Of The Carboniferous Rocks Of The Central Appalachian Basin In Kentucky, Donald R. Chesnut Jr. Jan 1992

Stratigraphic And Structural Framework Of The Carboniferous Rocks Of The Central Appalachian Basin In Kentucky, Donald R. Chesnut Jr.

Bulletin--KGS

A series of seven cross sections across the Central Appalachian Basin in Kentucky, Tennessee, Virginia, West Virginia, and Ohio was constructed in order to determine a stratigraphic and structural framework of the Carboniferous rocks for the basin. Oil and gas well logs, coal-company core descriptions, measured sections, and mapping of surface geology were used to construct these sections. New surface and subsurface faults, folds, and flexures were identified.

New, formal and informal lithostratigraphic nomenclature was introduced to clarify the stratigraphic framework. Formalized nomenclatural changes are (1) elevating Breathitt Formation to Breathitt Group, (2) dropping the Lee Formation, (3) elevating four …


Distribution Of Foraminifera And Pollen In Coastal Depositional Environments Of The Southern Delmarva Peninsula, Virginia, U.S.A., Han Jun Woo Jan 1992

Distribution Of Foraminifera And Pollen In Coastal Depositional Environments Of The Southern Delmarva Peninsula, Virginia, U.S.A., Han Jun Woo

OES Theses and Dissertations

The coastal zone of the southern Delmarva Peninsula exhibits a wide variety of barrier island system subenvironments. This study investigates whether 20 a priori subenvironments can be distinguished from each other on the basis of abiotic environmental variables, pollen assemblages, living foraminiferal populations, and total (living plus dead) foraminiferal assemblages.

The physical data collected from the coastal zone were subjected to canonical variate analysis which discriminated 83% of the stations in 19 groups. These groups were clustered into two internally overlapping sets which represented the inside and outside of the inlet.

Twenty-two pollen types were found in low-energy marsh and …


The Stratigraphy And Sedimentology Of The Sentinel Butte Formation (Paleocene) In South-Central Williams County, North Dakota, Wesley D. Peck Jan 1992

The Stratigraphy And Sedimentology Of The Sentinel Butte Formation (Paleocene) In South-Central Williams County, North Dakota, Wesley D. Peck

Theses and Dissertations

Approximately 163 meters (535 feet) of the Paleocene Sentinel Butte Formation crop out in southcentral Williams county, North Dakota. To determine their mode of deposition and stratigraphic position within the formation, twelve stratigraphic sections were measured. These strata were deposited in alternating fluvial and lacustrine environments as determined by sedimentary structures, lithology, lithologic sequences, and fossil occurrences. A fining upward trend in grain size of the tabular sandstones, and the identification of epsilon cross-stratification in the tabular sandstones support a fluvial origin for some of the strata. The strongest evidence for the interpretation of lacustrine deposition is the presence of …


Sr-Isotope Record Of Quaternary Marine Terraces On The California Coast And Off Hawaii, Kenneth R. Ludwig, Daniel R. Muhs, Kathleen R. Simmons, James G. Moore Jan 1992

Sr-Isotope Record Of Quaternary Marine Terraces On The California Coast And Off Hawaii, Kenneth R. Ludwig, Daniel R. Muhs, Kathleen R. Simmons, James G. Moore

United States Geological Survey: Staff Publications

Strontium-isotopic ratios of dated corals have been obtained from submerged reefs formed during Quaternary glacial periods off the Hawaiian islands. These data, combined with data from deep-sea sediments, tightly constrain the secular variation of marine 87Sr/86Sr for the past 800,000 yr. Although long-term trends are apparent, no significant (>0.02‰), rapid (<100,000 yr) excursions in 87Sr/86Sr were resolved nor did we observe any samples with 87Sr/86Sr greater than that of modern seawater. Strontium in mollusks from elevated marine terraces formed during interglacial periods on the southern California coast show resolvable and consistent variations in …


The Sloan Sag: A Mid-Miocene Volcanotectonic Depression, North-Central Mccullough Mountains, Southern Nevada, Hayden L. Bridwell Dec 1991

The Sloan Sag: A Mid-Miocene Volcanotectonic Depression, North-Central Mccullough Mountains, Southern Nevada, Hayden L. Bridwell

UNLV Theses, Dissertations, Professional Papers, and Capstones

In the Hidden Valley area of the north-central McCullough Mountains, southern Nevada, mid-Miocene andesite and dacite domes, flows and pyroclastic units (the Sloan volcanics) partially fill a sag in the underlying Hidden Valley volcanics. The 13.5 km diameter sag formed during and/or after the eruption of the Sloan volcanics. Sagging was accommodated by a combination of movement on the McCullough Wash fault system, and subsidence into evacuated chambers.

Major, trace and rare-earth element geochemistry suggests that the rocks of the Sloan volcanics belong to four groups, each of which were produced by partial melting of chemically distinct sources. With the …


Ua66/8/3 Geogram, Wku Geography & Geology Aug 1991

Ua66/8/3 Geogram, Wku Geography & Geology

WKU Administration Documents

Newsletter created by and about the WKU Geography & Geology highlighting activities of faculty, students and alumni.


A Geophysical And Geological Study Of The Farmville Triassic Basin, Charles G. James Jr. Jan 1991

A Geophysical And Geological Study Of The Farmville Triassic Basin, Charles G. James Jr.

OES Theses and Dissertations

The Farmville basin is one of many Triassic basins which are found along the eastern coast of North America, and is the largest of the central string of basins in Virginia. Meta-volcanic and metasedimentary rocks of the Chopawamsic Formation, as well as felsic intrusives are the primary lithologies surrounding the basin. A detailed gravity survey was conducted along six roads that trend approximately NW-SE, across the basin. Geologic, gravity, magnetic, and radiometric data were used to develop a kinematic model. Gravity anomalies were isolated using two-dimensional harmonic analysis methods to isolate the local, and regional anomalies. This analysis indicates that …


A Geophysical Study Of The Easternmost Piedmont: Brunswick County, Virginia, Mark A. Corbin Oct 1989

A Geophysical Study Of The Easternmost Piedmont: Brunswick County, Virginia, Mark A. Corbin

OES Theses and Dissertations

Gravity and magnetic models indicate that a steeply dipping, mylonitic shear zone recognized by reconnaissance mapping in the easternmost Piedmont of Brunswick County, Virginia is a listric fault. A pronounced 3 to 5 mgal Bouguer anomaly high is associated with the fault zone. A band of N10° trending aeromagnetic anomalies delineate the areal extent of the fault zone. The fault zone flattens eastward over a short distance to a depth of 15 kms where it joins a near horizontal surface that cuts across the region. This surface is herein interpreted to be a decollement. The fault zone of this study …


Slope Stability As Related To Geology At Rainier, Columbia County, Oregon, James Douglas Gless Jan 1989

Slope Stability As Related To Geology At Rainier, Columbia County, Oregon, James Douglas Gless

Dissertations and Theses

Rainier, Oregon, has experienced problems in the development of residential and commercial sites, utilities, and transportation facilities as a result of slope instability. This study of slope stability at Rainier was conducted at the request of city officials.


The Stratigraphy Of Late Quaternary Deposits In The Payan Mining District, Narino, Colombia, South America, Richard Alan Barringer Apr 1987

The Stratigraphy Of Late Quaternary Deposits In The Payan Mining District, Narino, Colombia, South America, Richard Alan Barringer

OES Theses and Dissertations

Late Quaternary terrace deposits along the Rio Magui consist of cobble or pebble gravels with thick volcanic ash caps. These gravel terrace deposits unconformably overlie a cemented volcanic tuff (Ananias Formation), and are subdivided into two formations (Antigua and Panambi formations) based on the cobble lithology and size, depth of weathering, geomorphic relationships, and heavy mineral assemblages. Carbon-14 dates from wood suggest that the Antigua fan deposits are older (greater than 40,000 YBP) than the lower Panambi alluvium (less tahn 25,000 YBP) which is restricted to lower terraces within the modern river valleys.

Two separate ash units identified by differences …


Development And Application Of Some Quantitative Stratigraphic Techniques To The Coos Bay Coalfield, A Tertiary Fluvio-Deltaic Complex In Southwestern Oregon, Willard Sidney Titus Iii Jan 1987

Development And Application Of Some Quantitative Stratigraphic Techniques To The Coos Bay Coalfield, A Tertiary Fluvio-Deltaic Complex In Southwestern Oregon, Willard Sidney Titus Iii

Dissertations and Theses

A computer technique for interpreting geophysical logs of drill-holes in quantitative lithologic terms has been developed and tested on the deposits of the late Eocene Coaledo Formation, a well-studied fluvio-deltaic complex in southwestern Oregon. The technique involves the use of induced and natural gamma logs for separation of coal and claystone from coarse-grained detrital rocks and the use of the ratio of resistivity and natural gamma responses (defined here as the "grain size index") to divide the coarse elastic rocks into a series of textural classes corresponding to the Wentworth-Odden particle size scale.


A Paleoenvironmental Study Of The Salem Limestone In The Vicinity Of St. Louis, Missouri, Douglas J. Van Brunt Jan 1987

A Paleoenvironmental Study Of The Salem Limestone In The Vicinity Of St. Louis, Missouri, Douglas J. Van Brunt

Masters Theses

“The Salem Limestone (Meramecian) of Mississippian age in the vicinity of St. Louis, Missouri is composed of a variable sequence of limestones deposited in shallow waters adjacent to scattered positive elements. This unit varies in thickness from zero up to 160 feet.

A medium to coarse-grained calcarenite is the dominant rock-type of the thesis area and is most abundant in the central and southwest regions. Stratigraphic sections in the northern region are more dolomitic, increasingly brecciated, and contains numerous secondary features. The southeast region is thinly bedded and composed of greater amounts of micrite formed by algal activity or direct …


A Gravity And Magnetic Study Of The Crooked Creek Cryptoexplosion Structure, Crawford County, Missouri, Charles Edward Woodbury Jan 1987

A Gravity And Magnetic Study Of The Crooked Creek Cryptoexplosion Structure, Crawford County, Missouri, Charles Edward Woodbury

Masters Theses

"The pre-Pennsylvanian structure at Crooked Creek consists of a complex, vertically faulted ring of Cambrian and Ordovician sediments with a central uplifted core. The center of the structure is strongly deformed and contains shatter cones, brecciation, and other signs of extreme shock.

A magnetic low over the center of the structure suggests that igneous material was not involved in the formation of the structure, and this is corroborated by core analysis. Gravity data indicates several small gravity lows, possibly associated with areas of brecciation, circling the flanks of the structure. As in the magnetic data, there is no indication that …