Sponsored by the Geomorphology Specialty Group
Association of American Geographers 102nd Annual Meeting
Chicago, Illinois, March 7-11.
Aeolian Geomorphology III
Paper Session 4117
Friday, 3/10/06, from 12:00 PM - 1:40 PM
Geomorphology Specialty Group
Coastal and Marine Specialty Group
Jean Taylor Ellis - Texas A&M University
Deanna Van Dijk - Calvin College
Deanna Van Dijk - Calvin College
12:00 PM Author(s):
*Harry M. Jol - University of Wisconsin-Eau Claire
Sandy Vanderburgh - University of College of the Fraser Valley
Derald G Smith - University of Calgary
Curt D Peterson - Portland State University
Karen G Havholm - University of Wisconsin-Eau Claire
Jim B Phipps - Grays Harbor College
Abstract Title: Coastal Foredune Genesis and Growth: A Ground Penetrating Radar Perspective
An understanding of the genesis and growth of coastal foredunes is an immense undertaking resulting in complex questions to answer. In a humid coastal environment, vegetated foredunes develop immediately landward of the high-tide line, parallel to the beach. The morphology of these foredunes, as noted by earlier authors, is primarily controlled by sediment supply, wave energy regime, wind conditions (strength and direction), vegetation type and density, and sealevel changes. In many locations, a foredune forms as a new dune on a low beach ridge with a vegetation/swash/log debris base and receives such a substantial sand supply from the beach that the vegetation cover is limited to predominantly a pioneer dune/beachgrass community. In this review of ground penetrating radar (GPR) experiments of foredunes at various locations worldwide, we examine the internal stratification and thereby the history of their development. Two GPR acquisition systems were utilized: Sensors and Software pulseEKKO 100 and 1000 with antennae frequency ranging from 50 - 450 MHz. The GPR data reveal dune stratification resulting from foredune aggradation/migration/progradation, scour surfaces of various types, and buried paleosols that record periods of stabilization between phases of dune activity.
Keywords: Keywords: ground penetrating radar, coastal, aeolian, foredune
- 12:20 PM Author(s):
*Suzanne DeVries Zimmerman - Hope College
Ryan Zietlow - Hope College
Edward C. Hansen, Dr. - Hope College
Abstract Title: Seasonal Sand Deposition and Vegetation Patterns on a Large Parabolic Dune on The Southeastern Shore of Lake Michigan
Erosion pins were used to monitor the pattern of sand deposition on the lee slope of a large (45 m high) parabolic dune southwest of Holland, Michigan.Almost all sand movement to the lee slope occurred during fall and winter; sand deposition was concentrated on the upper slope. During the first year, the two storms with strongest winds were associated with 49% of the annual sand deposition. Ice between grains allowed steep slopes (37o) to be preserved on the upper slope until the spring thaw when mass wasting moved sand to the lower slope. Sand accumulated in an arc around the dune axis with the maximum deposition occurring at the axis (~ 1 m) and decreasing to less than 5 cm at those points along the limbs where the walls of the interior trough were more than 10 m high. Maximum deposition along the dune axis implies topographic steering of wind, an effect which has been confirmed by measurements of wind directions in the dune. Vegetation sampling transects based on sand deposition patterns were established on the dune; species diversity, distribution and community composition were determined from quadrant sampling and percent cover estimates during the growing season. Vegetation patterns reflect the pattern of sand deposition. Pioneer species marram grass and field horsetails dominate in regions of high sand deposition. Red-osier dogwood, beach pea, Gillmanís goldenrod, bouncing bet, grape, and basswood communities appear in zones of intermediate to low sand deposition
Keywords: coastal dune, parabolic dune
- 12:40 PM Author(s):
*Bradley R. Schrotenboer - Michigan State University
Alan F. Arbogast - Michigan State University
Tanya J. Cabala - Alliance for the Great Lakes
Duane Johnson - Ford Motor Company
Abstract Title: Locating Alternative Sand Sources for Michiganís Foundry Industry: A Geographical Approach
Numerous large coastal dune fields occur on the western coast of Lower Michigan. These dunes are an important ecological, geological, and recreational resource in the state. They also serve as a significant source for foundry sand in Michiganís automotive industry and thus have been intensively mined in some places. Although Michigan contains extensive sand deposits besides those in coastal dunes, no studies have yet investigated alternative foundry sources from a distinct geographical perspective. In this context, a collaborative study was recently initiated between Michigan State University, the Alliance for the Great Lakes, and Ford Motor Company to see if suitable alternative sources of foundry sand exist. Acceptable alternative sand deposits must yield at least 12 million tons of sand and lie within five miles of existing rail or barge networks. Therefore, transportation patterns and water well log stratigraphic data were incorporated into a GIS to create economic suitability maps. From these maps, over fifty sites were selected from inland dunes and outwash deposits and sampled at depths of up to 15 m. Samples were tested for grain shape, grain size distribution, acid demand value, and chemical and mineralogical characteristics. Preliminary results indicate sufficient volumes of sand in close proximity to existing transportation networks, as well as desirable grain shapes. Ongoing tests will reveal the extent to which these sands can serve as replacements for coastal dune sands in the foundry industry and the extent to which acceptable sand deposits statistically correlate to specific landforms.
Keywords: sand mining, Michigan, dunes, glacial outwash, applied geography
- 1:00 PM Author(s):
*Emily Timmons - Hope College
Edward C. Hansen, Dr. - Hope College
Timothy G. Fisher, Dr. - University of Toledo
Abstract Title: Chronology of Eolian Activity in a Coastal Dune Complex Near Holland
Radiocarbon ages from paleosols, OSL ages from buried sand, and distributions of clastic sediments in lakes near eolian dunes are used to constrain dune chronologies, growth and migration. We studied four sediment cores obtained by piston vibracoring from two small ( 20%) in sand concentration. Sand lamina ages were constrained by 21 radiocarbon ages from terrestrial macrofossils, and are consistent with the eolian chronology developed from OSL and age-dated paleosols but provide greater resolution of eolian activity. An active period of dune growth began with the Nipissing transgression in the Lake Michigan basin, corresponding with many sand laminae within the cores. A relative paucity of sand laminae suggests a slowdown in eolian activity during a low lake stand between 3900 - 3200 cal. YBP. A dense concentration of sand laminae corresponds to the growth and migration of massive parabolic dunes near the shore between 3200 ? 2700 cal. YBP. Dune stabilization indicated by a lack of paleosols is consistent with few sand laminae in lakes between 1800 ? 400 cal YBP. Three sand peaks in the last 400 years indicate dune remobilization, synchronous with the burial of the Holland paleosol. This study demonstrates how multiple techniques can be combined to give a high resolution chronology of eolian activity in a coastal dune complex.
Keywords: Coastal Dunes, Lake Michigan, Lakes
- 1:20 PM Author(s):
*Michael M. Benedetti - University of North Carolina Wilmington
J. Michael Daniels - University of Wyoming
Jonathan A. Haws - University of Louisville
Caroline L. Funk - Stockton College
Abstract Title: Geomorphic interpretation of late Paleolithic occupation in the Estremadura region of Portugal.
The coastal Estremadura region of west-central Portugal provides examples of how soil, geomorphic, and geologic interpretations are beneficial to studies of human occupation history and landscape change. The region has been occupied by humans since the last glacial maximum, and has been intensively cultivated since Roman times. Although archeological evidence confirms human activity at inland sites during the late Paleolithic (generally during the last glacial maximum), little evidence exists for occupation and resource use along the coast. We argue that this scarcity may result from geomorphic processes that obscure the archeological record. Our primary objective is to characterize the geomorphic and stratigraphic contexts within which late Paleolithic archeological sites are likely to be preserved. These include: (1) late Pleistocene beach deposits exposed at 20-40 m ASL in bluffs along the coast; (2) buried erosion surfaces, often associated with a gravel lag deposit, beneath a Holocene dune sheet that covers the landscape within 10km of the coast; (3) weathered bedrock surfaces on uplands that have been eroded by cultivation; (4) Pleistocene valley fills adjacent to former lagoons that were filled by historical sedimentation; and (5) colluvial deposits found in caves and rock shelters. The potential for preservation of archeological evidence in these settings is confirmed by an initial survey in the region.
Keywords: geomorphology, Quaternary science, archaeology
Session Description: This series of three special paper sessions are co-sponsored by the Coastal and Marine Geography (CoMa) and Geomorphology specialty groups. The research presented in the paper sessions cover a broad spectrum of spatial and temporal scales within aeolian geomorphology.