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Brooks Ellwood, Ph.D
Professor

Geophysics, Rock Magnetism, Stratigraphy, Geoarchaeology

Education:

Ph.D. 1977.  University of Rhode Island, Graduate School of Oceanography.
MS 1974.  University of Rhode Island, Graduate School of Oceanography.
BS 1970.  Florida State University, Department of Geology.

Academic Experience:

1999--      Professor and Chair, Department of Geology and Geophysics, LSU
1988-99   Professor, Department of Geology, UT Arlington
1997-99   Professor, Sociology and Anthropology at UT Arlington (joint appointment)
1989-92   Professor and Acting Chair, Department of Geology, UT Arlington
1983-88   Associate Professor, Department of Geology, UT Arlington
1981-83   Associate Professor, University of Georgia
1977-81   Assistant Professor, University of Georgia
1976-77   Research Associate (Post Doc), Ohio State University
1970-76   Research Assistant, University of Rhode Island
1969-70   Teaching Assistant, Florida State University

ellwood@lsu.edu

Office: (225) 578-3416; Labs: (225) 578-4399; 5999

Brief Summary:

Rock magnetic/geophysical/geoarchaeological studies in Europe, Africa, Asia and North America. Current projects include the study of bolide impact evidence in marine sections; development of new magnetosusceptibility global correlation techniques in North Africa, Europe and the US; study of Global boundary Stratotype Section and Point (GSSP) localities; geoarchaeological and paleoclimate studies applied to Middle and Upper Paleolithic (Quaternary) cave sites in Europe; and magnetic studies applied to a broad range of lithologies.

Selected reviewed published research by topic below.
 
  Ellwood3

As a geologist you never know what you might find!  Natural in Wrangell-St. Elias National Park and Preserve, Alaska.
 

EXAMPLES OF WORK OUR GROUP, FACULTY, STUDENTS AND ASSOCIATES, ARE DOING:

Global Correlations:

     Working in conjunction with an international group of colleagues, we have been using magnetic susceptibility (MS) measurements of Paleozoic and Mesozoic marine rocks, in conjunction with biostratigraphic control, for high-resolution chronocorrelation and have named the method MagnetoSusceptibility Event and Cyclostratigraphy (MSEC).  MSEC is a composite of the MS record of marine strata and the coeval biostratigraphic record, and MSEC chronozones have boundaries which are isochronous (see Ellwood et al. 1999; 2000; 2001, and Crick et al., 1997; 2000, 2001; 2002 as an examples of this work).  MS in marine sediments is a measure of the concentration of magnetic grains that are dominated by the detrital input of lithogenic material due primarily to global sea level changes, climate, and sea floor/basin subsidence.  In those sections we have examined, MSEC event trends of increasing MS magnitudes correlate well with episodes of regression, while trends of decreasing MS magnitudes correlate with episodes of transgression.
     The primary controls on the MSEC signatures in marine rocks are sea-level (base-level) changes and climate.  MSEC events can result from global sea-level fluctuations causing (1) base level changes and therefore corresponding changes in detrital influx into the worlds oceans, (2) changes in global climate, or (3) result from local small-scale tectonic effects.  During times of sea level regression, base level is lowered and increased erosion brings an increased detrital component into the marine system, primarily from rivers.  This material is then dispersed by bottom currents throughout ocean basins and MS magnitudes rise.
     Much of the MSEC work has concentrated on Devonian rock sequences from North Africa and Europe but the method is applicable to marine rocks of any age for global correlation.  Early work has demonstrated clear correlations between multiple sections from Africa, Europe and North America, including both pelagic and neritic environments.

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Research in Morocco, North Africa

Reference: Ellwood, B.B., Crick, R.E., and El Hassani, A., 1999.  The MagnetoSusceptibility Event and Cyclostratigraphy (MSEC) Method Used in Geological Correlation of Devonian Rocks from Anti-Atlas Morocco, AAPG Bulletin, 83, 1119-1134 (includes cover photo).

 Environmental and Geoarchaeological Studies:

A new method for inter- and intrasite correlation and paleoclimate estimation, that can also help resolve age ambiguities within and between archaeological sites, has been applied to archaeological sites from Albania, Belgium, France, Portugal, and Spain.  This method, magnetosusceptibility event and cyclostratigraphy (MSEC) is based on magnetic susceptibility (MS) measurements of sediment samples.  In this context, the MSEC method involves building a composite reference section (CRS) from samples collected at archaeological excavations and for which the MS is measured.  This MSEC CRS then serves as a standard to which MSEC data from other excavations can be compared.
     Our early MSEC research has provided three important results.  First, this work has shown that MS data can be used in a number of environments for correlations between excavations.  Second, this research has shown that MSEC data can provide a paleoclimate proxy, as confirmed by independent climate indicators.  Third, results have shown that MSEC data can be used to for determining relative ages of sediments associated with human occupations.  When combined with isotopic ages and paleontological data sets, the MSEC CRS has the potential for estimating ages within sites at resolutions greater than in the past.  This is possible because MSEC zones provide time-synchronous boundaries to which MSEC data from individual excavations can be compared.      Early work on sediments from Middle/Upper Paleolithic and Neolithic cave sites has shown that fluctuations in MS values result from changing climate (temperature/moisture), causing regional changes in pedogenesis of sediments forming outside of caves or deep rock shelters.  These sediments are then eroded and deposited within sites and are the primary control on the observed MS in collected samples.  Lower MS magnitudes have been shown to represent times of generally cooler climate, while warmer times yield higher MS values.  Distinctive fluctuations in MS magnitudes and trends are the basis for intra- and intersite correlations while also indicative of paleoclimate trends.


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Block on the left is research we have done in Carlsbad Caverns National Park. Here we are recovering a 3 m core from the Texas Toothpick, a standing speleothem located in Lower Cave at the end of the Big Room in Carlsbad Cavern.

In addition to this work, we have been involved for a number of years in other types of geoarchaeological investigations, using electrical and magnetic methods.  This work includes investigations of environmental hazards, in locating buried metallic objects, and in monitoring the flow of underground contaminants. These methods have also been used to delineate features indicative of human occupation such as graves, fire pits, building sites, and other areas of ground disturbance. Some sites have been dated using paleomagnetic measurements (archaeomagnetic dating). Electrical resistivity methods are used in basin analysis, in archaeological site surveys, in delineation of burial sites, and in determining the depth of subsurface horizons which are likely pollution migration pathways, such as the water table. Magnetic surveys have been used to identify cultural material at archeological sites previously located by other means.  These surveys are designed to help archaeologists and engineers evaluate the subsurface at reduced cost and to isolate buried objects using remote sensing techniques.  A number of studies also involve research in National Parks.

Selected Reviewed Published Research by Topic (alphabetical):

Air Pollution Studies
Basalts
    a. general
    b. marine
Cave Research
Coal Research
Exploration Geophysics
General
Geoarchaeology
Global Correlation
Granites
Hydrocarbon Research
Instrumental
Magnetic Field Studies
Metamorphic Rocks
Mineral Studies
National Parks
Paleoceanography
Paleoclimate
Paleontology
Sediments
    a.   general
    b.   marine
    c.   paleoceanography
Statistics
Stratigraphy
Structure
Theory
Video Programs
Volcanic

Air Pollution Studies
 


Basaltic Rocks/General
 


Basalts/Marine
 


Cave Research
 


Coal
 


Exploration Geophysics/Geoarchaeology
 


 

General
 


Granites
 


Hydrocarbon Research
 


Instrumental/Theory/Techniques
 


Magnetic Field Studies
 


Metamorphic/Structure
 


Mineral Studies
 


National Parks
 


Paleoclimate
 


Paleoclimate/Paleoceanography
 


Paleontology
 


Sediments/General
 


Sediments/Marine
 


Sediments/Paleoceanography
 


Stratigraphy/Correlation
 


Statistics
 


Video Programs
 


Volcanic Rocks
 

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