William F. Kean

Botanical iron minerals correlation between nanocrystal structure and modes of biological self-assembly

Plants, like animals, use and store iron in their cells. Yet, the composition and structure of the plant-iron biominerals, constituting the inorganic cores of phytoferritin, have remained unknown. Transmission electron microscopy (TEM) and diffraction studies of subcellular phytoferritin, extracted from disrupted plant cells, indicate that phytoferritin occurs as crystalline magnetite (Fe 3 O 4 ) ϵ-Fe 2 O 3 , and hematite (α-Fe 2 O 3 ), with typical sizes of single crystallites in the 1 — 50 nm range and agglomerate grain sizes up to 4 μm. The three-dimensional agglomerates are built with different biomineral nanocrystals in three distinct modes of biological self-assembly: 1) ordered magnetite; 2) semi-ordered mixture of magnetite and ϵFe 2 O 3 ; and 3) random hematite. These self-assemblies correspond to prior TEM reports of crystalline, paracrystalline and amorphous phytoferritin arrangements in sectioned cell samples. A fourth plant-iron biomineral, tentatively assigned as calcium ferrate hexahydrate, has a morphology and diffraction patterns distinct from the phytoferritin aggregates. We do not attribute the plant iron observed in this study to be the results of atmospheric pollution.

Contributions of wood ash magnetism to archaeomagnetic properties of fire pits and hearths

Magnetic studies were conducted on a variety of plant ash and ash material from fire pits to investigate the possible contribution of ash to the magnetic signature of hearths. The measurements included magnetic susceptibility, remanence acquisition to saturation (SIRM), alternating field demagnetization of SIRM and remanent coercivity (Brc). We conclude from these studies that wood ash produces fine-grained magnetic iron oxides. These oxides are probably magnetic that is concentrated enough to add to the magnetic signature of hearths and fire pits. At one site (Ellicottville, New York), the ash layer exhibits a magnetic susceptibility that is 22 times greater than a control soil sample from the site. We attribute this large enhancement to repeated burns at the site which continued to add ferromagnetic material to the fire pit. The source of the magnetic material is probably phytoferritin from plants. The variation in the intensity of magnetic anomalies over ancient hearths and fire pits may in part be caused by the magnetic contribution from ash.

Urban Field Geology for K-8 Teachers.

Geologists have long appreciated the value of field trips. Likewise, the National Science Education Standards recommend them for K-8 science curriculum. Yet, few teachers avail themselves of quality field opportunities close to home. We presented summer institutes for urban teachers in Milwaukee that centered on several Lake Michigan beaches within the bounds of their school district. Field and laboratory activities were developed in the context of the geology of southeastern Wisconsin. As an example activity, we compared the sand from four different beaches for grain size, magnetite content, as well as fossil and modern Zebra Mussel shells. The different beaches show different characteristics that were related to their location and origin. We encouraged the good field trip teaching practices of “Teaming-Up,” reducing novelty space, and pre- and post-field trip activities. The teachers shared lesson plans and developed action plans for implementing the changes in their curriculum. We determined that the teachers in these three-week workshops increased their personal belief in their ability to teach earth science more effectively. They felt more comfortable with content material and found that action plans were an effective way to enact change regarding field trips in their curriculum and in their schools.

Urban Earth Science In Milwaukee Wisconsin

Earth science topics are always in the news and are ever present in our life. Yet earth science is frequently given poor or uninviting coverage in K-12 schools because of lack of expertise and/or for an apparent lack of local importance. With this in mind, individuals from the University of Wisconsin- Milwaukee (UWM), the Urban Tree House Project (UTH) and Milwaukee Public Schools (MPS) have collaborated to provide earth science materials for pre-service and in-service teachers that center on the earth science resources of Southeastern Wisconsin. These include field guides to local parks (particularly the Lake Michigan shoreline), web based virtual field trips, instructional videos, information on the local geologic environments and soils studies. The collaboration allows for similar instructional strategies and content presentation for both in-service and pre-service teachers through programs sponsored by UWM. The collaboration is being well received by all the stakeholders involved. The MPS teachers are energized by the newly discovered resources in their own urban backyard. MPS students are exposed to real-life applications of earth science. Pre-service teaching students appreciate the field experiences they have in class and the connection to MPS curriculum standards that helps make the learning experiences more meaningful.

Paleomagnetism of Sediment Cores from Cedarburg Bog, Wisconsin, and a Comparison with Cores from Lake Michigan

Abstract Four 10-m sediment cores from the Cedarburg Bog, Wisconsin, were collected for paleomagnetic measurement and carbon-14 dating. The paleomagnetic records for these cores are self consistent, with the intensity record affording the best correlation. These results are compared with sediment cores from Lake Michigan. The two sets of cores are unmistakably correlatable on the basis of intensity. The inclination correlation also shows common long and short wavelength features. On the basis of this correlation, we date certain member boundaries of the Lake Michigan Formation as follows: Waukegan–Lake Forest, 5,500 years B.P.; Lake Forest–Winnetka, 7,800 years B.P.; and Winnetka–Sheboygan, 9,700 years B.P.

On the Origins of Magnetic Excursions in the Great Lakes

Abstract Paleomagnetic studies of cores from Lake Michigan and Lake Erie exhibit possible excursions of the geomagnetic field at approximately 9,000 to 10,000 years B.P. and 12,000 to 14,000 years B.P. In this report, magnetic data and lithologic data from two cores from Lake Erie and six cores from Lake Michigan are presented. It is shown that the magnetic excursions are predominately associated with deepening waters which followed low lake levels produced by glacial advances and retreats. It is suggested that these excursions are the result of slumping and/or flowing of lacustrine and glaciolacustrine materials, rather than of changes in the magnetic field.